NDA? (*looks around*) The rest of this forum didn't get that memo.
I'm going to vote that iCloud is 'good-okay', for now.
At the moment I have it set up only to sync my bookmarks, because I use them daily as a temporary archive-retrieve system for reading articles, saving photos for later, etc. So far, Reading List is working beautifully: nearly instant MaciPhone sync.
As for everything else...
Apple first needs to make a concrete method for the process necessary to get calendar/contact data synced into iCloud, and then synced to the devices. After getting tons of duplicates upon my first try, I didn't attempt to figure out the order needed to get this working. (Though, I imagine it's something like: 1) have calendars in iCal, 2) sync iCloud account to those calendars, 3) delete iCal's database, 4) let everything (iCal, iOS iCal) sync from iCloud. Repeat for Address Book.)
I've also been using it for iPhone backup, instead of iTunes, and it uploads fairly quickly. I'm not sure it's ready to be considered 100% stable yet, but it's working, and just recently I restored from it. It took a long time, and not
all of my apps' data had returned, but it was impressive. This will be immensely convenient once most iDevices are iOS 5, and then subsequent iOS versions are released and people buy new iDevices. It's like an iOS Time Machine.
I haven't been able to get any sort of iDisk functionality working though. I have iCloud set up, and I can see how much of the 5GB is used (from the iPhone backup) in Lion's new 'Mail etc' pref pane, but it isn't user accessible at the moment. However, I do have a random '[numbers].members.btmm.icloud.com' server in my Finder network, but can't do anything with it.
Photo Stream seems to be functioning too, though I've only tested it via an iPhone restore (I haven't updated iPhoto).
Once it gets polished, it will be amazing. It's what MobileMe should've been for the last three years (although I will miss the iWeb part).
