It's alright. The plot of each episode generally carries a positive message, although I have found some to have subtle undercurrents of negative traits, such as acting on your first impulse or disregarding other's feelings.
As for the main character, Po, I think they really minced his character in this series. I know it is just a cartoon, but he acts drastically different. In the movie, he was kind, caring, funny, and brave, a character one could describe as having a "heart of gold". However, he had his imperfections, providing children with a positive role model that isn't perfect, such that children don't feel that such a way of life (aside from the kung fu... I mean acting) is not possible. In the cartoon, however, Po is a bit mean, and tends to disregard the feelings of others. In all, he has gone from being a dynamic, positive character to a negative, cardboard character. For that matter, nearly all of the characters have become static and simple.