I will preface these remarks by acknowledging that I have probably made a complete hash of trying to set up and use iCloud with my iPhone 3GS (iOS 5) and 24" iMac (Lion 10.7.2) and iTunes (10.5).
None-the-less, I find iCloud to be poorly executed, unreliable, unnecessarily and unpleasantly surprising, destructive, poorly documented, and dare I write it: Microsoft-like. Furthermore iCloud smacks of Orwell's "1984": now that I'm in it's not possible to get out and erase my presence in iCloud. Or, as the Eagles sang in Hotel California, "'Relax,' said the nightman, 'We are programmed to receive. You can check out anytime you want, but you can never leave.'"
I initially set up iCloud on my iPhone shortly after installing iOS 5, using my existing iTunes appleid. On the morning of October 17 I turned everything on in Settings>iCloud and watched my iPhone battery go from 97% to 10% in seven hours(!) Every time I so much as looked cross-eyed at my iPhone it would write something to iCloud. So I turned everything off and observed that battery consumption returned to what I am used to. (Meanwhile, I had not yet activated my iMac in iCloud.)
About this time I figured out that the new Reminders app is a Really Good Thing. I created several Lists and transcribed dozens of Calendar events (that were, in fact, reminders) to Reminders. I then performed weed abatement in Calendar and cable-Sync'd with my iMac. Presto! Much cleaner calendars. I then decided it would be nice to have my reminders show up in the iCal Reminders side bar on my iMac. Even though the iPhone User Guide For iOS 5.0 Software describes, on page 95, how one enables Reminders sync-ing in Settings>Mail, Contacts, Calendars, this function is not implemented in iOS 5. A kindly My iPhone tech told me the only way to sync Reminders is through iCloud.
Meanwhile, I decided that my iCloud information would be more secure if I created a new appleid just for iCloud. I would create a new iCloud-only appleid and use it to activate both my iPhone and iMac in iCloud. (Oh God, what a mess this effort would create.)
I quickly discovered that I could not change my iCloud appleid in Settings>iCloud, but would have to delete my iCloud account and start over. So I did. I then dreamed up a new appleid. As all the on-screen documentation used "email@example.com" I decided to create a mailbox at me.com. I got precisely nowhere: The second My iPhone senior technician I talked to got around to explaining that any email address containing "@me.com" is considered a MobileMe address and is inelegible for use with iCloud. (Aw <expletive deleted>.) Mind you, getting this far consumed over four hours of my time and that of three Apple technicians spread over two days.
But that's not all!
It's now Monday morning, October 24. When I activated my iMac in iCloud, my laboriously-created Reminders disappeared! Vanished. Six completed reminders dating from October 17 (when I first turned on iCloud in my iPhone and fiddled with the Reminders and other apps) were all that remained. In my iPhone. In iCloud. In iCal. That was really annoying. What was disappointing was discovering that iCal's Reminders functionality is seriously deficient and, in my opinion, not worth using. So all the preceding effort to get iCloud up and running was (in my opinion) wasted. I really have no need for, nor desire to use, the other iCloud facilities (with the likely exception of Find My iPhone--that seems like a good idea).
But wait, there's more!
Monday evening, October 24, being thoroughly disenchanted with iCloud, I set about disentangling my iMac from iCloud. (Queue "Hotel California".) I started un-checking the boxes in System Preferences>iCloud. When I got to Address Book, iCloud wiped it clean! That's when I discovered that I cannot recover Address Book Groups from Time Machine. All 900 vCards, yes. The 29 Groups into which they were sorted, no. (Aw <expletive deleted>.) iCloud had a complete Address Book in Contacts, as did my iPhone. I didn't see any way to tell iCloud to push its complete Contacts down to Address Book. Fortunately for the many fine My iPhone techs, the switchboard was closed for the day. I put my iMac to sleep, shut off the modem, and broke out the Wild Turkey. Nighty-night, everybody!
Now it's Tuesday morning, October 25. I turn on my modem, wake my iMac, and retire to the kitchen to brew some coffee. A while later I return to my iMac to check email and perform my other morning rituals. Lo and behold! My Address Book is restored to its former glory! iCloud (bless its black heart) has saved me.
Tuesday afternoon. My iPhone. Another senior tech. Another hour-and-a-half on the phone. My iMac is now cut-off from iCloud. iCloud still has an empty Calendar and an empty Contacts. It seems that if one stumbles into the iCloud quicksand one can never extricate oneself completely. ("Hotel California" reprise.) But I'm free! Free, you hear! Free! Except for Find My iPhone. That's a good thing. It's the only item turned on in Settings>iCloud. It can find my iPhone. All the boxes in System Preferences>iCloud are un-checked.
"Never more!" cried the raven.