I think Johnston is a good director but not outstanding. A lot of his movies I've found very good but others very boring and forgettable. He's basically like Spielberg-lite. I mean that's not the worst thing in the world either. I'm sure they will get someone decent for Thor 2. Though I don't see why it can't be Branagh again since he doesn't seem to be very busy and he did a good enough job with Thor which was pretty much a breakout hit last year.