Care to explain why you think he is an idiot?
He did beat Martha Coakley rather convincingly. He served as a State Senator for several years. He even voted for several Dem bills.
Coakley was a bad candidate who ran a terrible campaign - I'll hunt around for a great article I read a year ago outlining the tremendous mistakes she made.
As for Brown, he has a difficult time answering questions about policy in a cogent fashion. I have seen him on several occasions give answers which show that he has no real understanding of the underlying issue at all, and several which are really just embarrassing.