It’s truly wonderful. This is such a delightful, endearing and ingenious movie. *'Klaus'* really grabbed my attention—I was captivated right from the beginning. It’s fantastic, featuring some superb hand-drawn animation. The performers, Jason Schwartzman among them, all deliver strong performances. It was great to see how it ties together the origins of Santa Claus, Christmas and everything associated with it. When you consider it, the concept is fairly straightforward, but it's presented in an intelligent and agreeable fashion. The final scene is especially heartwarming. Beyond its emotional core, there’s also humor present, and the rhythm is absolutely perfect. Schwartzman is amusing as Jesper, while J. K. Simmons provides a very capable portrayal of Klaus. Joan Cusack was enjoyable too, as Tammy. The actors are likely lower on the list of what makes this film so good, but that's only because it has other, more prominent strengths. It’s always nice to find an exceptional animated movie outside of Disney productions; it helps foster important competition for them.

Source on TMDB