Good, but highly inconsistent. Some worlds pull of the three-partner heist idea very well while others become very tedious run and fetch missions for the most part. Still suffers a bit from mini-game madness and some missions, especially anything involving Bentley, suffer from the fact Bentley is both slow, weak, and awkward to control. Unlike first Sly, little incentive to go back and replay missions compounded by the fact that missions are not readily replayable (you need to play through the entire world again to replay missions).
For the good stuff: Murray and especially Sly are great characters to play. Sly in particular controls a bit more tightly than the previous game and you can pull off very stylish move combos when the world permits. Slowdown from the first game is pretty nonexistant and the game often strikes the right balance between stealth and action. Boss battles are for the most part pretty inventive again, with the high watermark going to the second-to-last boss battle which is reminiscant of a more action-packed Dungeon Keeper.
Asthetically, the same high quality polish as the first game, with the animated clip sequences and the very nice voicework back in spades. Art style has changed, but personally I enjoyed the new look better after getting used to it.
