Current MobileMe users have currently 20GB of storage at hand, however this is going to increase to 25GB when they move to iCloud.
MobileMe and iCloud accounts are different in design, but as Macrumors point out, they do have some overlapping aspects.
iCloud is continuing to support Calender, Contacts, Mail, Bookmarks, Find My Phone and Back to My Mac, but will drop support for iWeb Publishing, Gallery and iDisk. iCloud will add iTunes In the Cloud, Photo Stream, Documents In the Cloud, iOS Device backup and Automatic downloads of apps and books.
As the services move across Apple will support MobileMe until the end of June 2012 and they will be moving services over to iCloud with an extra 5GB (25GB) free of charge. According to Macrumors people may choose to downgrade before the shutdown and not get charged.
Kitguru says: iCloud something you would use?