Using Win XP SP2 (fully tweaked) on a semi-ancient P4 2.0 Ghz with 1 GB RAM...
LR v1.0 was working smoothly. Happy.
LR v1.1 would often hang after about 15-20 mins of work, CPU usage climbing to around 90%. Import at times refused to work, either via the open dialog or dropping files into the library. Export - in most cases just nothing. And so on ...
Went back to LR 1.0. Happy.
Just to (re)state the obvious for anyone passing through here who is thinking of updating:
1) it is essential you read the release notes [ see link on the Adobe DL page ]
2) look through the relevant sections of the Help documentation.
3) make sure you understand how LR databases work and how to back them up - just in case.
For anything else (or more):http://www.adobeforums.com/cgi-bin/webx/.3bc2cf0a/
While v1.1 was up and running I did get a chance to test some of the new features and yes, some nice things to look forward to there.
My guess that the marketing guys at Adobe pushed for an early the release date when v1.1 wasn't quite cooked. It would have been more appropriate for Adobe to release v1.1 as a beta with a proper bug report system - an easier ride for all concerned. I just hope they consider that option for future updates.