Yeah, I guess I understand what people are saying, he's definitely not as silly as he was in the other movies, but I think that's a good thing. I still stand that he does and says plenty of silly stuff in the nolan movies, he's just a lot more subtle with it. Aside from all the stuff I mentioned in my earlier post, there's little moments like when he crashes the party at wayne manor, he takes a wine glass as he's terrorizing the crowd of people, spills it all out and takes a sip out of the empty glass. Asking them where harvey dent is becuase he "needs to talk to him about something, just something little." Or when he finally finds rachel and he says "why hello beautiful" as he fixes his tattered hair walking towards her. Or just his constant re-telling of how he got his scars always ending up being a completely different story, even though it was also very disturbing. Or how he laughs at inappropriate times.
His performance is just filled with these little nuances that really do make him quite silly, again just a much more subtle and darker silly.