I have already tested it with the free 60 day trial and was not really impressed by its performance (unavailability, lag) and its functionality (Outlook sync is simply not working, see here).
Now I tried to crate my final account with the activation number contained in the package, and everything seemed fine until I tried to logon:
Invalid member name or password. There is no way to get in…
Needless to say that I’m getting slightly upset having paid a considerable amount of money for a service that has that many flaws (working in the IT business I want to be nice with Apple and give them some time to iron out the quirks (e.g. Outlook sync) but it is a whole other story if you just can’t use the paid for service at all)
I sent an email to the Apple support (the guy on the phone – very polite – could not help me) at 8 am CET today.
I’ll keep you posted on what comes back.
Update : It has been 24 hours and still no news from Apple Support
Update 2 : In the meantime I got the activation sorted out : I had to redo it with the same activation number as before and now I have access to MobileMe (Outlook sync is still not working, see also here in the Apple Forums)