In my opinion, the best game in the Assassin's Creed series to date. The character of Ezio is wonderfully developed with an excellent backstory. You can't help but empathise with him and you quickly find yourself highly invested in the success of a character who grows and evolves as the game progresses.
The plot and gameplay have improved leaps and bounds since the first installment, which laid good foundations, but did not deliver on its potential. The setting of Renaissance Italy is fantastic, with cameos from some of the period's influential players. Visually the game is very appealing when considered against other games released at the same time.
Basically, an excellent plot, excellent game play and an enigmatic lead character, who I consider the best video game character since Nintendo's Mario!