We use Airdrop a lot for sharing large files over our local network, for that it works great, and is a lot more efficient than Dropbox. But I agree that it would be more useful if it's an open protocol.

With respect to iCloud - it makes little sense to make it generally available. It's an free add-on (except iTunes Match) that ties you into 'the Apple platform'. If you and your applications use iCloud for synchronization, and it's limited to iOS and OS X, there is one more hoop to jump through if you want to switch to another platform.

Whether Apple succeeds on that front, we have to see, and depends on things such as adoption by third-party application developers.