AC II definitely improves on its predecessor, but gameplay still feels a bit underwhelming.
Assassin's Creed II easily joins the top of that list with its immaculate art direction and photo-realistic depiction of Renaissance-era Italian cities. The writing staff also ups their game with a twisting, mystery-filled tale that would give an X-Files episode a run for its money in the intrigue department. Lead protagonist Ezio Auditore da Firenze is a more personable frontman this time around and generally gives you an avator to root for. Character development in general is a little flat, as you'll frequently be hunting down figures you generally don't care or know much about, despite the game's numerous cutscenes and codex pop-ups. Your allies are also a little cardboard-ish in personality, so don't expect any meaningful attachment to any characters you encounter in this franchise. AC II surprisingly airs on the longer side of single-player adventuring, easily clocking in at more than 20 or 30 hours of gametime, depending on how extensive your side-questing takes you.
The semi-open world of AC II is generally a pleasure to explore, if not quite as rewarding or expansive as something like Red Dead Redemption or Fallout 3. Your travel options are taken farther off the rails than something as tightly directed as Uncharted 2, as you can freely advance throughout most of the world at your own pace. Trouble is, there just isn't that much to do outside of plowing through the core story-based missions. There are a lot of inconsequential side-missions and random collectibles if you're into that sort of thing. Everything you collect has an incremental effect on how much income you generate per 20 minutes of gametime (cleverly handled as "rental income" on your family's estate), but the "unlocking" system, as it is, never feels as addictive or empowering as other examples of this, like the Ratchet & Clank series or various multiplayer shooters.
Combat in the first Assassin's Creed was a mess, and AC II offers a slight improvement. It still feels clunky and unsatisfying, frequently devolving into non-responsive button mashing as you take on any group larger than 1 or 2 enemies. Weapons and gadgets remain unimpressive to use. And while platforming feels great from an animation and control perspective, it's still largely limited to scaling buildings and jumping between rooftops. A series of six tombs (unrequired for completion purposes) offers a more impressive platforming experience, taking you through imaginative cave and cathedral interiors. It's a shame these natural environments and creative sequences aren't integrated more widely in the overall game.
All in all, AC II is a notable, if not spectacular, example of one of the most ambitious genres in gaming today.