I am finding the whole iCloud universe to be somewhat uneven at this point. some things work very well and others for no reason that I can see, don't.
I have tried iPhoto on 3 different Macs (all running Lion and up to date)
1) 2009 MacMini - iPhoto 9.2 locks up and goes into a loop of startup and almost immediate crash if I enable Photostream. The only way I have found to get out of it is to use iPhoto Library Manager to create a new (empty) library and launch iPhoto using it. I then attempt to enable Photostream (which disables Photostream on my real library). The new library immdediately crashes but I then switch back to my old library and things are good again.
2) 2007 MBP - same as for the 2009 MacMini
3) 2011 MBA - iPhoto 9.2 launches and announces the library needs to be upgraded. It pretends to do it for about 15 seconds then goes into Event view as if all is well. Photostream will not enable (but at least it doesn't lockup, crash or burn). Everything else seems to work, but the next time I start iPhoto 9.2 it does EXACTLY the same thing again, including telling me the library needs to be upgraded.
Aperture works with no problems.
iMessage is great but my wife gets messages sent to her on both her iPad and iPhone (desirable). I only get messages on my iPhone unless I start the conversation from my iPad (in which case I only get them on my iPad).
I have been through the settings several times and can't figure this one out. Our setups and settings appear to be identical, but they don't perform the same.
Wifi sync so far doesn't
Documents works fine, but as you know if you have used it requires some manual intervention on the Mac end of things.
I'm not dissatisfied, or even complaining all that much, more just sharing the current state of affairs with iCloud roll out at my house. I am pleased that I upgraded to IOS 5 and love the new features and believe that updates from Apple will eventually smooth out the bumps.
IMO this is one release they maybe rushed a little on (perhaps trying to get it out and up while Steve was still with us--perhaps not) and so it is a little rough around the edges.
Glad things are all working well for you; wish they were here as well, but expect rapid improvements.