When you have castled on opposite sides of the board, one of the major factors is who can open up the pawns in front of the enemy king first. I think black had an opportunity at move 13 to open the g-file by playing 13. ... gxh4 14. Bxh4 Rg4 and double the rooks on the g-file. Notice that since the f-pawn is pinned it doesn't support the g-pawn if it is pushed to g3.
At move 17, instead of blundering, white could try 17. a4 a6 18. a5 Ba7 19. b5 and now it is white who is opening files leading to the black king. White's rooks and queen will go over to that side of the board and try to infiltrate black's king position.
My analysis is that I have a slightly better position, as I am in a position to trade off his strong bishop for my weak bishop, my forward knight is in the middle instead of on the wrong side of the board, my dark bishop is lined up against his King, and my King-side pawns are on the attack giving me plenty of space there. Also, my two rooks have open space in front of them allowing them to be doubled in 2 moves instead of 3.
Like I said, I don't know positioning very well, so I could be totally off base with my analysis. So please, pick it apart. :) Thanks!