When I first played Batman: Arkham Asylum, the first game in the new Batman series, I was pleasantly suprised by how good a game it was. Graphics were good and gritty - very Gotham City. And most importantly the fighting sequences were fun, combo-filled and fluid in a way I've never seen in any other game. The game was based mainly in Arkham Asylum, Gotham City's most dangerous prison for nutcases like the Joker.
Fast forward to Batman: Arkham City, which brings us out of Arkham Asylum and into Batman's great city. Along with a much larger space to explore, comes new mechanics. The most notable being the ability to now glide (pretty much fly like in Assassin's Creed 2, except the flying mechanics in Arkham City is MUCH better) takes you to greater lengths in shorter time. I must admit when I first tried it, it felt really awkward with the swoop down and glide up movements. However, once I've gotten used to the glide mechanics, it really feels great in terms of movement from one point to another... quite empowering really! Especially when you combine it with attack moves when flying down on enemies.
The same fluid combat that made Arkham Asylum popular remains in Arkham City. It's always a joy to see Batman in combo mode and the moves seem almost "Matrix"-like when optimised. There are a lot of side quests you can do to increase experience points in order to upgrade abilities and there is a reasonable amount of variety in the side quests. Sometime later in the game, you get to play as Catwoman too, which is a fun diversion from standard Batman. That said, I still prefered Batman!
And if you wish to get your money's worth, you could sink 10s and 10s of hours into the game due to a plethora of sidequests such as the glide challenges and the Riddler's quests to find all the question marks - which is likely to take you forever! Of course this depends on whether you're an obsessive compulsive. While I enjoyed the story end-to-end, I don't think I have the patience to run through the entire blimmin' side quests, as it required too much dedication.
Batman: Arkham City, like Arkham Asylum, remains one the best superhero games available. Voice acting is also great, and who would've thought Joker would have the voice of... Luke Skywalker (Mark Hamill)?!! I give Arkham City an 8 not because it's not a near-perfect game, but rather, it's due to the similarity in gameplay in general to Akrham Asylum. If I've never played Asylum, I'd give it a 9 or 10. That said, it's well worth it.