No. It wasn't so much her. And the seriousness wasn't it. I went into the film with high expectations because afterall, this is Batman. Anyway, I just found it too slow paced for my taste.
I totally agree with you about the slow pace. They were trying to cram too much into the first movie. Batman's childhood, the subplot love interest with Katie Holmes, how Batman became Batman in the mountains, then the fight against his teacher at the end, and the numerous time invested into the character developments.
I think this sequel will be MUCH better now that those originations were established in the first film. I think Heath Ledger will steal the show. He's a talented actor who excels at getting into his roles in terms of preparation. I'm looking forward to seeing it. I really like the darkness these new Batman movies have. This new joker looks really sadistic and creepy.