From the indepth reviews I read on that specific version it's mainly loading and frame times that were quite improved along with lower CPU and memory usage, Average and minimum FPS didn't go up that much if any though.
I enjoyed them. They definitely were poorly implemented in a game that had such good dynamics and flow, but I still enjoyed them to a degree. I understood that they had to include the Batmobile. Eventually a Batman game without it would start to raise serious eyebrows. But I wish they'd selected a different route with it and included it less. It was basically an invincible tank on ice with a pellet gun. That description doesn't sound like good gameplay.