I think Marvel's great strength in putting their film world together has been they've had the faith in the characters to sell the movies so they haven't felt the need to bring in much in the way of obvious "Big Names" either as the leads or behind the cameras.
Most of their directors wouldn't have been the first choice for big tentpole movies (even if they'd have been the fan choice), and on that score it's worked out great for Wheedon. The Avengers has saved his career from the very real danger of going down the Chris Carter path.
And he was equally good for the film. The problem (or advantage if you regard the sort of fee that, say, Michael Bay can claim for each Transformers film as obscene) is the director doesn't have very much negotiation leverage. Marvel/Disney have the confidence to know they can find some fresh faced and, yes, cheaper, director who they can be sure will make a successful film for them.
As for if The Avengers is as good as the hype... I don't think any film that succesful ever can live up to its reputation. But despite me not finding it perfect (the big city battle lost a lot of impact for me from being so similar to the one in Dark of the Moon) it was a damn fun movie.