The sound is with my old B & W CDM1 boxes for the price range more than neat. Clear that one hears at the High End considerably finer things.
Since I was on a fairly extensive dispose classical collection of almost 2 TB of data (mostly FLAC or Apple losssless) I realized that indexing the library would take some time to complete. First, I was pleasantly surprised that this was already completed after about 60 minutes. However, they comprised a maximum of one third of the total collection: The data alphabetically by composers in appropriate directories from AZ and an extra folder for compilations. But I have not managed to bring more than 12 directories between E and Z to display.
To be fair, it must be said that Sonos points in a FAQ on its website on a 65,000 titles limitation that should not decrease in long paths and a large number of metadata by a percentage not mentioned.
However, there is a workaround for the problem: use on the iPod or iPad app PlugPlayer for about 4, which asks the media server on the NAS and the music files via UPnP streaming commands directly to the Sonos. Conclusion: For large collections never buy the Sonos Controller, but the money for an iPod touch (version 3 should also work here) Create.