Think I've done everything apart from the Riddler and the mystery serial killer ones now, and still yet to dig into the combat challenges.
There are an insane amount of Riddler challenges/trophies etc (you think you're nearly done, then you realise you've barely scratched the surface) - done the majority of them, but not sure if I'll ever have the time or patience to do them all, despite my OCD-like tendencies willing me on. I binged on the game big-style over Christmas, but rarely get the time in my day to day life to spend much time on games, so we'll see.