After having almost completed AC2 recently I must admit I've changed my tune.
I really don't think much was done to rectify problems with the original: missions are still repetitive, free running is not as effortless as it should have been, climbing countless landmarks is still pointless, and many of the new additions (i.e. the villa, weapon upgrades, outfits, etc.) are all quite superfluous. And what's the point of having all those sets of armour when the best one is obtained halfway through the game?
Combat was also very bland for me: button bash until the guard drops, or just dodge behind him for a one-shot kill. Perhaps I'm just feeling let down after the brilliance of Batman AA's combat mechanics?
This all carries a very big 'meh' factor after the hype AC2 has been given; it might as well be a reworking of the first game. And once you strip away the fluff (especially things like finding feathers or doing courier/race missions), it might as well be.
Not to criticise the MyGaming review, but I honestly wouldn't have given AC2 anything more than 70%, and that's just because of the obvious level of research and historical accuracy that was put into the whole experience.
IMHO, the next in the series needs to focus less on the complex plot and have a simple yet compelling story ala Prince of Persia, make the free running a lot more integral ala Mirror's Edge (with a dose of Prototype), and implement a combat system that doesn't completely suck the big one.