Yahoo Games has reviewed Batman: Arkham City at a 6 out of possible 5, saying it "improves on the original so much that it feels like gluttony." This isn't the first time such hilarity has graced games reviews; PSM3 France gave Uncharted 2 a 21/20. For what it's worth, it's definitely worth a high score - typo or not - from the amount I've played so far. Expect a piece on that tomorrow alongside the UK launch.
It's out now on PS3 and 360 in the US, with the PC version launching in Europe on November 18. A Wii U version is also on the way.