Full Assassin's Creed ahead! Sort of.
Arkham Asylum was great. Arkham City is good. The open world doesn't take long to navigate around at all - you can do it in a couple minutes from one side to the other - and there's really bugger all to do inside it beyond beating more dudes up. All it really does is give you a chance to run about as Bats, which is awesome for the first hour before you end up just legging it backwards and forwards between buildings like it's some kind of interactive load screen. The game is still incredibly linear and I didn't get the feeling I could affect the story at all as much as delay it with side missions. Having to trek back and forth through the city makes the linearity even more irritating.
All the gizmos are back from Asylum. There might be a couple of new ones - I can't remember exactly what was in Asylum - but there's nothing massively different that sticks out. You start with most of your gadgets ready and the upgrade system doesn't do anything dramatic, nothing that you'll use much anyway. There's no real sense of getting more awesome as a character, but you're flippin' Batman to start with - how more awesome d' you wanna be? I think the fake open world gives it a little bit of an RPG feeling, but all the fun stuff of an RPG - freedom, morality, character building - is nowhere to be seen. Fighting is still amazing, though I really don't like the sound effects. They're not weighty enough. Punches sound like little taps. This is Batman, dudes! He should goddamn PUMMEL people in the face!
The story's OK. Nice central idea, good ticking clock, but it does suffer from having to cram all the villains in (as Asylum did). There are a couple of cameos from other Bat-universe types, but it would've been nice to have them utilized better. How about a Sonic 2-style team-up with Robin? There are some Catwoman bits, but they're not important to the story and feel a bit jammed in. She controls very well, though, and is fun to kick people with.
Good game! It does new stuff and has a larger scope, but it all just makes it a little more boring.
