Arkham Asylum is quite fun in my opinion, especially if you're a big fan of the comics/animated series. The combat is simple, but the fights are great to watch and play, especially when you really get to using your punches, counters, stuns, and batarangs (and you really need to eventually). Plus a lot of time it's better to not hop down among the later gun-toting, knife-wielding convicts and just use your sneaking skills to dominate.

However, I would be remiss if I didn't recommend you look into Uncharted 2 heavily. I haven't played it and probably won't for some time, but with so much positive buzz you would be wrong to at least not look into since you have a PS3.