Came here and saw that the update was ready, but was puzzled that it hadn't shown up in my appstore updates when I checked earlier (Have been going back every few hours waiting for this one!!!) I deleted my existing version and then tried to install 2.1 but got a message saying I needed to update iphone firmware to 3.1.3. I guess that if I had already done this the new version of the app would have automatically appeared in my update list.
All now updated and installed - been playing for a few minutes and loving it ! Sync on the fly is fast (added over 1000 albums in less than 15 seconds) and all seems to be working fine. Cover art and lyrics too. Can fall back on the containers option if I ever need to. List and search functions working beautifully. Thanks so much Chris - you have brought a lot of happiness to me and my Soundbridges. If I could pay for the app again I would do so without hesitation
(Using 3 x M1000, QNAP TS-109 with Twonky 4.4.17, Iphone 3GS - 32gb)