No he was not evil. He was a Jedi to the end. All Jedi are not alike, but he was fighting the good fight until he was killed - truly devastated by Anakin's actions. But Anakin was doing the right thing in that moment - remember he wanted to take him into custody, which is the Jedi way. His motive may not have been good (I think he wanted the Emperor alive as he was the only hope for Padme), but as he pointed out before killing Dooku, that was not the Jedi way. So Mace was in the wrong to want to kill rather than capture. Of course, he may have felt capture was beyond his ability and killing was the only alternative, but then he should have alerted more Jedi to assist.