Very boring, disconnected shooter.
Go.
If you mentioned free roaming on large environments, you know what Gangs of London is missing. It's a string of disconnected, inconsequential action sequences tied together by... I was going to say an awful plot, but on second thought they're not tied together at all.
The best part of the game is mission one, where you get to kill Melendi (at least on the Euro version, I guess they kept that). Melendi happens to be a real and pretty bothersome pop singer from Spain, so if you're Spanish you'll find some pleasure in riddling him with bullets as the game's first and very stupid boss. After that, it's all downhill. You have teammates that couldn't shoot an elephant from the inside, driving missions with less freedom to choose your path than a GT race and lots and lots of ugly menus, cutscenes and loading times breaking up your brief and uninspired gaming sessions. In short, don't buy this game. Don't rent it. Don't look at it. It's not worth it.