I certainly agree. It was a little bit of a letdown after that initial Death Eater scene in DH1 was finished and I realized that that was probably the last we would see of him in the whole movie. His performance is one of the few, perhaps the only, aspect of the films that has never disappointed me. His characterization has been the most consistent of any in the movies: consistent with the books and consistent across all the movies. I don't remember how I imagined the character before Alan Rickman was cast, but I do remember thinking at the time that it was perfect casting, and now I will never be able to think of the character in any other way.
ALSO, I noticed on the credits of DH1 that J.K. Rowling got producer credit on this movie for the first time. I wonder if that partially accounts for its awesomeness. (Uncredited rewrites, perhaps?) I looked it up and noticed that she also has producer credit on DH2. That makes me feel better about the final movie being as good or better than the penultimate one. I'm a little nervous about that because DH1 was so good that it raised my expectations again for DH2, and it will really be a letdown if the final installment doesn't live up to expectations. Although the trailer I watched last night looks very promising.