I know they've said they're trying to ground it in reality, but I just don't see it from the trailer. It has that colorful "popped off the pages of the comic" look to it, and the dialogue seems a little too campy. And the fact that they're resorting to using motion capture CGI to create Iron Man(for god knows what reason) makes me think it's just gonna be one big CG fest by the end.
All in all, I see this film being more in line with Spider-Man than Batman Begins. The problem, however (as others have said), is that Iron Man doesn't have mass public appeal or even recognition. I think Favreau is overestimating this thing, really. Especially with the talk of a three picture deal. The general public just doesn't have enough interest in Iron Man to care. Now maybe if he makes the first film really unique and special(like what Nolan did with Begins) it would spark interest, but if it just turns out to be a run-of-the-mill summer superhero action flick, it's not gonna happen.