This is one of the best games of the last few years. What really makes this stand out is that it would be a great game even without all the Batman stuff, as it's a near-perfect blend of a diversity of different tried-and-true game aspects. If I had to describe it, I'd say it's a mix of Bioshock's atmosphere and style, Just Cause 2's grappling/glider insanity, Splinter Cell's stealth, Half-Life 2's playable cinematics, Dead Space's camera and controls, Wolverine Origins's combat system (but much better), some really unique stuff you haven't seen before, and BATMAN. All of this being in an open-world environment, of sorts.
What results is a ridiculously polished game that is impossible to put down. I beat this game in nearly two straight days (10-12 hours), and I barely ever do that. Plus, this game has one of my top 10 favorite video game moments ever.
I think it's obvious that you should not miss this one if you consider yourself a gamer. Especially in a gaming drought like this one.
In a sentence:
Combines many successful elements into a surprisingly polished, gorgeous and captivating game.