Nick Cage did Raising Arizona and Con Air was a bit of stupid fun, that said Ghostrider was pants!
Downey Jr is perfect for Stark if you ask me, former alcoholic and a bit of a nutter. From what I've seen of the previews I think it'll be good, I've read every bit of Iron man that I could get my hands on and I like what I've seen so far. As for his previous work, he has done some great films - anyone see Chaplin?