Did I say he was a bad actor? No. I said it wouldn't be a stretch for him to play an alcoholic, Stevie Wonder could see that Robert Downey Jr. has had drug problems.
I have nothing against the guy, I've liked several of his movies. That being said, from the looks of this trailer I'm very unimpressed. It doesn't look good to be. Granted, I'm not an Iron Man fan boy so I haven't followed the comics throughout the years. But in my mind I never pictured Tony Stark as portrayed by Robert Downey Jr. in this trailer. He may very well be nailing the character, but either way, this movie doesn't look good to me.