I just finished "Dreams of Empire." I really liked all the pseudo-Roman trappings in the story. There's a strong murder mystery at the beginning and some great battle action towards the end. However, it often feels very light on character development. Jamie & Victoria don't get much to do. Even the Doctor's presence sometimes feels a bit light in the story, despite the fact that he's often at the center of the action.
Currently, I'm working on the new 3rd Doctor novel "Harvest of Time" by Alastair Reynolds. I'm not too far into it yet but Reynolds has just absolutely nailed all of the characters. The Doctor himself hasn't gotten much to do yet but Jo feels spot on. And the Master oozes charm just as he always did whenever Roger Delgado was on screen.