After letting the story sink in for a day or so, I've come to realize how much I enjoyed Cutter.
I liked the fact that he was quite equal to Nate in the fact he is intelligent and obviously knows his shit. In the Uncharted series, for the most part, Nate's companions always seem a step behind Nate in that department, leaving it to Nate to mutter to himself about clues/where to go next.
He is also quite witty, in a different way then Nate, of course, but still he had me laughing at some of his one-liners.
He just seems like a good chum, a decent guy. The sort of bloke you'd like to have a beer with, then go and rob some tombs and shit.