I read a review that said the second Bioshock was good but not as good as the first or as shockingly innovative. Seems to be a fair review unlike the fanboy adoration of ME2 which is a very good game but story wise not as good as the first but has better gameplay mechanics.
I just hope Arkham Asylum 2 is as good as the first but sequels are almost never better than the first except in the case of Empire Strikes Back.