Finished the game last night, now I'm going to complete a few side-missions, finish off the remaining Riddler trophies and go onto NG+. Overall, I loved it, but as amazing as the game is, by increasing the scope I feel that Rocksteady sacrificed a part of what made Arkham Asylum such a focused action adventure game.
I think the open world is a double edged sword - on one hand, it allows for a much more free experience and for a whole lot more for the player to see and do, but on the other hand it loses some of the focus and intensity that made the first game such an enjoyable experience. Also, the pacing in Arkham Asylum was a steady build, whereas with Arkham City it starts at a high intensity and tries to keep that intensity going over the course of the entire campaign and, ultimately, doesn't succeed. I do love how rich and deep the world is with DC lore, and I got a real sense of wanting to explore every street, collect every trophy and complete every side mission, which at times seems at odds with the story as the urgency and pressure of the situation rises. It doesn't seem right hunting down Riddler trophies while Batman's fighting for his life.
Regardless of any misgivings, Arkham City is still a wonderfully satisfying experience. The look and feel of the place is spot on, and every building and rooftop practically oozes with the iconic Batman style and history, plus, the general mechanics of playing as Batman have been tightened, expanded and refined from the original to such a degree that, while often overwhelming in it's scope, the options afforded the player are remarkable and Rocksteady have succeeded in creating not only a combat system that beats the competition and shows them exactly how it should be done, but they have also succeeded in creating a large and engrossing open world that begs to be explored and is lovingly peppered with DC lore and more content than you'll find in most of the big budget titles released this season. For me, it's going to be difficult for any game, and certainly any other 3rd person action adventure, to top Arkham City in the foreseeable future.