Everything worked and integrated well on my iOS devices, but OSX was a mess. Apple's cloud services are half-baked, things are not syncing realiably, the functionality is very limited (i.e. I can't share documents between my computers as I do with Dropbox; iPhoto doesn't sync at all).
While I agree that iCloud for document storage is a complete train wreck, that doesn't mean that all cloud services are. Given the Dropbox API that was just announced, I'd say that document syncing is a lot harder than what we though. If Dropbox (Dropbox!) avoided the issue, then I'd say Apple just bit off more than they could chew.
Honestly, though, I use Dropbox instead of iCloud storage because I like their philosophy of a single syncing folder, rather that data/application silos. Plus I use a lot of Windows PCs, so if I used iCloud, I wouldn't get complete access.
Back on topic...
Mail, contacts, calendars might not be as robust or as feature filled as Google alternatives, but they work well. iTunes Match had a few issues to begin with, but I haven't heard any complaints recently.