The best part of the game really has to be the humor and the time spent on making it an excellent licensed product. Although there are no animations between levels, there is a story that is voiced by the show's actual characters. In addition, all the voicework and music throughout the game is straight out of the original show, so the humor is spot on with what you'd expect from a South Park product.
This could potentially be it's strongest or weakest point though since if you aren't a fan of the show, this game won't really appeal to you too much. Even if you aren't a fan of the series, the game still features an impressive amount of content, and incredibly challenging gameplay, which should make for a good time for any strategy game fans.