Until clone wars and rebels, Maul didn’t have a character. He had 2 lines of dialogue in a 2 hour movie. The animated shows and comics gave him some MUCH needed character development.
I have to say, I loved Maul in both Clone Wars and Rebels. Those were some of the best episodes. (Except when Maul killed Satine. Really Maul, of all the ways he could exact revenge on Obi-Wan, he had to go with killing Obi-Wan's love interest?)