From where I stand, Mark Meer performs much better as Shepard. That might be bias considering I mostly play as him, but to me, he personifies the role of the stoic defender of humanity. He shows limited emotion and he doesn't exactly express himself the way we have been condition, but when he enters a room and delivers his line(preferably in renegade), you know he means business and that he's the only one to get it done. He definitely improves come the second game, exuding a smidgen more emotional weight(at least when he's comforting people, it appears like a real person, unlike in the first where it appears that he only knows of this emotion thing from watching bad romantic/drama movies). All in all, what he brings to the table is simply, for lack of a better word, the ultimate badass who no man would question in the trenches.