At first I planned to wait for OTA, but then I did the math and figured I would do it at 1am and stay up half the night fiddling around. So I downloaded and flashed (via Ubuntu 64-bit) and found it to be both painless and quick. All my photos and contacts were intact, but all apps and desktop configurations were wiped out. And I had to re-enter my Exchange server settings and resync.

That gave me a chance to winnow my apps a bit, but I know I am going to find something I missed. Most apps (including extras for conversations) picked up my old settings (which are stored in the home directory, which doesn't get wiped).

Impressions:
Inbox widget is nice. N900 found my Windows 7 pc on the network in media player. Meeting requests can be answered (hooray!). I can't find the Facebook sharing or the facebook widget (I use it to share photos to facebook, but I don't really love the widget). App Manager seems much snappier, and doesn't bring the whole device to a grinding halt (though I haven't added extras-dev yet).