The show itself was very well done. My favorite character was the Grinch (of course). The Grinch was played by Stefan Karl. From the FOX ENCORE magazine, he's best known for his role as the villain Robbie Rotten from "LazyTown". He played a wonderfully grouchy character and I loved the growls. He also was able to get the audience involved with his antics, which made the show more entertaining (and less scary) for the younger kids (my opinion).
My daughter's favorite character was Cindy-Lou Who. The youngest (and smallest) of the characters and cast. According to the ENCORE, the role is played by two actresses. I'm not sure which we saw (or if we saw both). Update: I found out that she was played by Clara Young.
Old Max (played by Bob Lauder) did a wonderful job of retelling the story of his youthful days. Told from the dog's point of view, the story takes a new spin. I really enjoyed "You're a Mean One". I wasn't expecting it to sound the same as in the movie, but with only minor changes, it sounded just like it.
Don't expect the scenes to be exactly the same as in the movie. They did a great job of recreating some of them. They did a great job creating new ones to go along with the story line. All in all, a wonderful show. If you get the chance, I recommend going.