The first Assassin's Creed game from Ubisoft Montreal was the source of much debate. Some thought it was a perfect blend of Splinter Cell-like stealth and Prince of Persia platforming. Others found it to be a good first effort that lacked in some key areas, sort of like IGN editor Ryan Clements' first San Francisco apartment. And then there were the haters, who apparently didn't care for either assassins or creeds, thank you very much.
Whichever category you fall in, you'll have to agree with this: Assassin's Creed II is better overall than its predecessor.