The libratone Lounge is the only genuinely high end AirPlay speaker available and it is absolutely awesome. So much so that I bought 2!
The sound quality is really good. I can only compare the sound directly to my pro audio recording system (genelec 8040a's + fireface audio interface) and although the quality isn't quite as high as that (it would be unreasonable to expect it to be as it is at a significantly lower price) the sound stage is much better. At higher volumes you can fill a large room. For lower volumes, I found that two units sounded much better in my lounge (9m by 5m). The airplay audio is in perfect sync between them.
The sound is balanced but you do not get the big thump at the bottom end, so if your main listening is hip hop you may wish to look elsewhere. I like the bass - it's refined and clear, and let's me listen at higher volumes without annoying the neighbours. The mid range is very good and the high end is fantastic - not exaggerated but just really crystal.
I had some issues with regular dropouts to start with but they have been resolved with the latest software. I rarely get dropouts now. Connection is fast - after you hit play, the music plays within 3 seconds or so. Pausing and volume changes are almost instant.
It's hard to review the Lounge without reviewing AirPlay too. There are limitations on the AirPlay system (that you don't have with Sonos) but that is Apple's fault not Libratone's - for example you can only stream to one speaker from an iDevice yet you can stream to as many as you like from iTunes. But on the plus side when using an iDevice you can use intelligent music apps like groove to get better mixes of your songs. And like everything Apple, it looks great and just works.
I highly, highly recommend this. Yes you can get a more expensive separates hi-fi system that will sound even better, and you can connect some device to get AirPlay working with it, but it will be a mess of wires and ugly. This is beautiful, simple and sounds fantastic to me - and I am generally very picky when it comes to sound quality.
I have recently bought this USD 1,300 Libratone Lounge speaker, it looks great, but it doesn't work. When you try to contact their 'support center' good luck to you. They have telephone support only in the us, for the rest of the world e-mail only; with the catch that they don't respond to their e-mails. It took me several months to track them down; eventually they acknowledged they had sold a defective product. Was there any remourse, apology or regret from Libratone head office in Denmark? Absolutely not, they couldn't care less about you or me. Especially staff member 'Henning Eithz' who couldn't bring himself to register that Libratone were in the slightest sorry for their terrible product and absent support for this high end USD 1,300 speaker or for the terrible customer experience I have had for the past months. So stay well away from these guys, if you think you may need any sort of support in future for your expensive hardware. They suck and don't give a damn about customers, Libratone dispatches defective products, Libratone ignores their customers who they sold defective products to, Libratone hopes that customers who pony up their USD 1,300 for the speaker will go away quietly. Summary: simply the worst support from any company that I have dealt with that tries to sell 'high end' products. Spend your money elsewhere - trash service from Denmark. ONE UNHAPPY CUSTOMER