I'll admit it up front - one of the key reasons I run Home Theater View is to get early looks at products like the Sonos system. I have been following Sonos since well before it launched. The concept is simple: Sonos takes the music you're already storing and managing on your PC and streams it to multiple locations around your house. The controller looks like an iPod, and, like an iPod, nearly anyone can use it. Each Sonos unit becomes part of a separate wireless mesh network - no WiFi needed, and setup consists of pushing a couple of buttons and letting Sonos do all the work. Sonos can play different music in each room, synchronize music to multiple rooms, or synchronize music to all rooms ("party" mode). Sonos can also accept music from any room and stream that back to any or all of the other units.
Sonos launched with a 2 room $1199 bundle: Sonos supplied a player/amplifier (ZP100) for each room and a controller (CR100), but expected consumers to BYOS (Bring Your Own Speakers). 
Sonos quickly heard that the BYOS strategy was DOA for a large segement of their target market, and rolled out Sonos-branded speakers for $179, or as part of a $1499 package for two amps, two pair of speakers, and a controller. The most recent update to the system is the ZP80 (pictured at right), which asks consumers to BYOA (Bring Your Own Amplifiers), which makes sense for economically integrating home theater systems and the like, which already have their own amps.
My test setup included a ZP80 along with a pair of ZP100's (pictured at left), a C100, and a pair Sonos Speakers. I have also hooked up a pair of Carver HT5.1 bookshelf speakers to one ZP100 and an Altec Lansing self-powered satellite-subwoofer PC speaker system to the ZP80.
Pricing: It Depends On Your Point Of View
What's unique about the Sonos' pricing is that it is either extremely expensive or a significant bargain, depending on your point of view. The Sonos ZonePlayers are $499 each for the ZP100 (the one with a built-in amplifier) and $349 for a ZP80 (the one without the amplifier). ZoneControllers cost $399 each, speakers are $179, charging docks for the ZoneController are $49, and a spare charger cables is another $19. The least expensive bundle is $999, which will be fine for many users, but expects users to both BYOS and BYOA.
This pricing makes technical early adopters scratch their heads and whine that compared to most streaming audio players, the Sonos is wildly overpriced. The Omnifi Simplefi I've had in the house for a couple of years, along with products from Pinnacle, Roku, Squeezebox, Linksys, and Apple, all cost between $129 and $299. Other options are mating an iPod with an Apple, Klipsch, or Bose audio dock: presto! music wherever you are. Finally, a cheapskate friend pointed out that boomboxes cost $39 at Target and can also put music in your room. If you'd be happy with a boombox - or even an iPod and an Apple HiFi - then the Sonos is clearly too expensive.
At the other extreme, a custom installed system can cost tens of thousands of dollars for a multi-zone setup that would cost $3,000 or $4,000 with a Sonos. In this respect, the Sonos is an incredible bargain.
The problem with the iPod and boombox is that they are single zone solutions - when you leave that room, you leave your music (and the boombox will only be able to play a fraction of your music collection, digitized or not). True, you could put a speaker dock in every room of your house and move the iPod with you, and if you live alone, this is a perfectly valid solution, but even then you need to move the iPod every time you leave the room, and it's hardly sufficient for a party.
The problem with most streaming media players is that they are either single zone (Apple, Linksys), cannot selectively synchronize music among multiple zones (all but the Squeezebox), have no display for selecting music to play (Apple, Linksys), have only a basic user interface (all), require a reasonable level of comfort with technology for setup (all except the Apple), and cannot accept music from remote sources and stream that around (all).
Where the Sonos Shines
In practice, the biggest drawback to most streaming music solutions is that they either need to be hooked up to a display, which limits where you can put them in the house, or they have a one line display and a rudimentary remote control, which makes moving through large music collections annoying. My wife was delighted when she discovered that with the Sonos 
she could quickly and easily create disposable mini-playlists by selecting songs and albums and putting them into the queue for just the two rooms she was working in that day. The large screen, scroll wheel, straightforward user interface, and multi-zone capabilities on the Sonos makes that scenario possible, and she discovered it without cracking the owner's manual. (Our five year old also likes choosing his music and routing it to zones throughout the house, but, then, he's five. Today's five year olds can master anything.)
Another neat trick the Sonos does is digitize and stream any source you feed one ZonePlayer to any or all of the other zones in your home. In practice, this means you can plug in a friends iPod, programmed with his party mix, and blast the music all over the house. The ZonePlayer accepts analog signals, so a favorite record or tape can be streamed around as well (though a preamplifier may be needed for phonographs to present a loud enough signal to the system). I even plugged in Nokia's latest music phone and a Kurzweil digital piano and used those as sources. The volume needed to be adjusted based on the source, but, other than that it works like magic.
Custom installed multi-zone audio systems can do all these things, too. There are several systems on the market that offer rich user interfaces, tech-free setup because someone else sets it up, and even remote source streaming. The problem here is one of price: to do what a Sonos does, you might have to pay tens of thousands of dollars for a sophisticated touch-screen based multi-zone system. A single Crestron controller costs more than a basic Sonos system.
Performance
The Sonos' sound quality was excellent across the board. The Sonos system could resolve enough detail that the weak link in the chain was typically the codec used to compress the music, not the Sonos wireless system, amps, or speakers. Having said that, it won't convince hardcore audiophiles to give up turntables, tube amps, and a pair of Vandersteen speakers and settle in for a dedicated listening session. But for the types of uses a Sonos system enables, the Sonos provides all the audio performance that's needed.
The speakers (pictured at right - click to enlarge) are actually quite a bargain. Bass is tight, highs are well resolved, and the midrange is pleasant. In a direct comparison, the Carvers were easily audibly superior with better bass and better presence in the treble, but the Carvers are a bipole design and were part of a system back in the day that retailed for a lot more than $179. I can easily recommend the Sonos speakers at their price point.
Installation and Setup
One key drawback is that a hard wired (Ethernet) connection is required from your PC to the first ZonePlayer unit. After that, Sonos has its own built in mesh network (technically not WiFi) that sets itself up automatically. Like all mesh networks, the more nodes (ZonePlayers and ZoneControllers) on the network, the stronger the network will be. The "first node: wired" restriction is not a problem for users who have Ethernet networks in their homes, but how many people does that cover? Worse, unless you're willing to string that first wire out of the computer room, the first ZonePlayer is redundant, as most PCs have speakers attached to them already, and the Sonos Desktop Controller PC software will happily drive them.
Aside from that limitation, the setup process itself is simple even for non-technical users. You do need a PC, but you don't need a home network. To get each unit to discover the network, you simply press the "mute" and "volume up" buttons found on the front of each unit. There are several companies working to make this type of plug and play wireless networking a reality for WiFi, but for now, Sonos' proprietary solution justifies itself well here. After the initial software installation on your PC, the system will literally updates itself and all the ZonePlayers and ZoneControllers with no user intervention required.
Each ZoneController can control all the zones in the system, but users should keep in mind that as they add zones, they'll need to add expensive ZoneControllers as well. There's nothing more frustrating than a powerful multi-zone system that's playing the wrong music in the zone you're in and the ZoneController is several rooms away. This may offend Puritans everywhere, but let's face it, once the remote control was invented, did you ever get up to change the channel again? Now think about going to the other side of your house to change the channel. This is why you need more than one ZoneController.
Over several months I did experience a handful of times where the ZoneController inexplicably locked up. Judging from the message boards, this does not seem to be a widespread problem, but it did give me the opportunity to test out Sonos' tech support. Using the web "call me" feature, the response was instantaneous and the support rep was knowledgeable. The culprit was diagnosed as wireless interference, but resetting the ZoneController also seemed to trigger a software upgrade (which happened automatically in the background) and there have been no problems since then.
Conclusion
Sonos is narrowly targeted: it doesn't do video. At all. In this respect, more capable systems may be a better investment. Interestingly, the best video storage system I have seen, the Kaleidescape, doesn't do audio. So there's clearly something to be gained in simplicity by restricting functionality to one type of media and doing it right. Still, consumers looking for a complete audio, video, and home automation solution will have to look elsewhere.
Even within audio, Sonos is constrained by DRM. REAL Rhapsody subscribers will be thrilled to discover they can access their entire music subscription library through the Sonos. But tracks purchased from iTunes or other Windows Plays For (Almost) Sure DRM stores won't play at all.
The Sonos may not translate well outside the U.S. It is easiest to justify for larger homes, like the McMansions that dot our suburbs where its multi-zone capabilities will be put to good use. It does not make as much sense for urban apartments or any type of home in space-constrained Japan. The system's flexibility only goes so far: Sonos needs water resistant units for the kitchen and bathroom, and an in-wall version for custom installation would be welcome as well. The system as a whole is a bargain but the accessories are badly overpriced, and at least one dock ought to be included with every controller from the outset. Finally, Sonos needs an all-wireless version, where the first unit is WiFi, and Sonos' mesh network takes over from there.
Sonos has done a good job of creating a system that should sell itself to upscale mainstream users, but as long as distributed PC-based audio is in the early adopter phase of market development, Sonos needs to do a better job in its marketing materials explaining how it differs from the Squeezeboxes and Rokus of the world.
As I finish writing this review, my wife is listening to - and singing along loudly with - The Bangles' "Eternal Flame" in the kitchen and family room, while I have The Strokes on in the office. She says we don't have to buy the review sample, but I'm not so sure...
-avi
