Same issues here.
Quote:
"The iCloud pane in System Preferences says "Starting..." and never finished.
Adding an account in OS X Mail prompts me for the Incoming Mail Server, even though it recognizes it as an iCloud account. Leaving leaving the field empty results in Mail unable to connect to the server.
Clicking on Mail in the iCloud web interface tells me I need to create an @me.com email address by enabling Mail in the iCloud System Preference.
I am using an existing MobileMe account (previously a .Mac account) which is my AppleID."
No working email on Mac & both my iPad & iPhone crash when going to Mail prefs and viewing account details (still receive mail ok on iOS devices)
Looks like its something wrong with the conversion process going from mobile me to iCloud