I'm playing it at the moment, I only started playing Saturday and I'm about 70% clear through the story mode. I think it's an amazing game, but I'm a huge Batman fan, so I may be getting more out of the story than someone not as familiar with the lore. There's a heavy undertone of the Grant Morrison "Arkham Asylum" from the 80's, little nods and winks and the overall plot. So again some of it might pass you by.
The combat starts off a bit wooden, but once you start coming up against the enemies with advanced melee weapons (knives and tasers rather than just pipes)it becomes more nuanced, and stops being a case of "mash square repeatedly". And the sections with the Scarecrow are mind-blowing. The stealth is slightly basic, but given how little fire the B-man can take it's necessary (and as long as you don't think about why so many gargoyles were built in doors) it's rather pleasing.
It's funny in a very dark way.
The weapons are fun, the "Detective" mode make you feel like you're doing the heavy brain work in the same way the computer in Portal makes you feel like you're doing particularily well even though you know it says the same to everyone. It makes the game deeper without impacting on the pacing, though you will find yourself playing with it on most of the time, so you miss some beautiful vistas. The asylum is dark, foreboding and in the cell blocks the atmosphere could be cut with a knife.
There's also plenty of "hidden packages", but the value of those depends on whether you're bothered. But there are enough easy one's in your path that's you'll unlock the back stories and there's enough of them in total (240 of the Riddler's challenges) that you could probably look for days. But again, that's if you a completionist.
I'd definitely recommend it, but the more you know about the Batman lore the more there is to get from it.
