Professor Lupin is neutral for me. Sometimes he's a drag and sometimes he's the coolest guy. I guess, though, that now that Sirius is gone he is all that Harry has left but...*shrug* he still kind of bores me sometimes.
I like how he's a werewolf, because it kind of gives his drab character a spice. And I also liked him 'PoA', because you really got to know him as more than just 'James' friend'. He's not just the kid on the side watching the troubles unravel, he's actually in the action, rooting on his friend.
Plus, David Thewlis is a good actor. He portrays Lupin very well and I think he deserves credit for bringing Remus to life.