I felt the same way. Man, that kid grew up fugly. Although I took the opportunity to play him as a grudge-holding Billy the Kid type psychotic and went around killing everyone I saw until I got tired of it. There's nothing for him to do.
The first time I played through the end I had left a couple of side missions half-finished, and I thought they could have done a better job of adjusting to the three year difference in time. The same fucking people were still standing there after three years!
It also would have been nice to have given the kid a handful of missions where he met people who talked about his father and did things for/with them, leading up to the revenge shootout, instead of just leading you straight to Ross. Or some things to do afterward, sort of a "Kid has to make his own name" type stuff.