There is a comprehensive thread at DigitalPoint forums named Adcenter - Horrible Customer Service where adCenter beta users discuss the issues they have with MSN's adCenter customer service. This is not the first time forum threads have been started complaining about features or service at MSN's adCenter. We have coverage of this back in November of 2005.
That is not to say adCenter wont get better. I have seen a strong effort in the forums by MSN to resolve issues. But does it always take a public display of disappointment to encourage good customer service? We have seen the same with Google and Yahoo!
Time will tell. Forum discussion at DigitalPoint Forums.