iCloud is up & running.
Like everything Apple, the interface is clean & uncluttered. You have the login page where you enter your Apple ID, or create one.
Once you are in, everything is just ready to go.
I enabled my iCloud through the iPhone [you can set it up from the iPhone or your computer] & a few moments later all my contacts & calendars were synced automatically to iCloud webpage, no exporting or importing was required. [Note: Only the calendars I had created on my Mac were synced, Google Calendars were not]
Contacts is similar to the Address Book app on OS X Lion & so is the Calendar. Find my iPhone works as before:Locate, Ping, Display Message, Play sound, Remote Lock & Remote Wipe. There is a slider switch for “email when found”. On the iPhone, find my iPhone is now in Settings->iCloud.
Note:It is possible to have different ID’s for App Store & iCloud. This is probably done because most users will have multiple Apple ID’s/MobileMe Logins etc. This is an extensive guide on how to manage multiple accounts you may have with Apple & how to set up iCloud with them.
For pictures you have Photostream. On OS X, iCloud will sync your iPhone pictures with iPhoto and Aperture [enabled after OS X 10.7.2 update & updating iPhoto/Aperture]. On Windows it will sync to your “Pictures” folder under “User” [you will need to download an iCloud update for windows]. You do not have a photo stream on the iCloud webpage.
Apple is providing 5GB of free data storage: Mail, Contacts, Documents & your iPhone backup to iCloud [if you enable it] will count towards this 5GB.
Music, Apps, Photos in photostream, iTunes purchases [books, music, TV Shows, apps, movies] will NOT add to this 5GB. So for most users 5GB should be more than enough. Of course, if you need more space you can buy it right from your iOS device [10GB will cost $20 per year; 20GB will cost $40 per year; and 50GB will cost $100 per year.]