Dammed, I knew someone would question it. I already feel the adrenalin rush when I think about what I experienced with them
Basically,...
Their mail servers were often not accessible, sometimes for several days.
Mail disappeared (I saw mails on the webmail inbox and when trying to download it through Outlook Express the program told me that there is no mail on the server. So I connected again to the webmail function and the mail wasn't there anymore).
Their spam filter (which you can't turn off) filtered mails I wanted to receive, e.g. subscribed news services (Wall Street Journal).
Their helpdesk people on the phone don't have a clue about anything and give you wrong answers.
When I reported problems through their 'contact the helpdesk' web function I didn't get an answer in half of the cases or they just wrote me back that I should call the phone support (which I did earlier, but they couldn't help me) or that they don't accept the problem as a problem (which in fact was that I couldn't connect to the mail server and they told me that everything works fine, but there definitely was a problem, because even their webmail function couldn't connect to the mail server and just showed me a "please try again soon" message).
They are too expensive and even more expensive when you use them outside of your home region for international dialup.