Pretty much the same look and feel as the first, but tons more to do. Your own villa (mini city + your manor) to upgrade and expand. The armor upgrades show on your character, you can dye your clothes, tons of weapons to collect, treasure maps, and lots of side quests/errands. The first 4 hours pretty much sets up the story and teaches you the game, but after that it really opens up.
I'd compare it somewhat to GTA IV, but in 15th century Italy. No cars, no guns, but plenty of tightly packed buildings to mob across, and tons of sh/t to do.
I never finished the first game because it got well..... boring.
you won't have that problem with assassin's creed 2. new weapons are introduced all the time, and collecting things gets you rewards. you gradually unlock new skills to use. 2 hidden blades and double ssassinations are sweet. tons of new enemies make you think on your toes, rather than just waiting to counter like in the first game. you also have doctors, tailors, blacksmiths, and not to mention leonardo davinci in the mix. it is far more realistic, allowing you to upgrade armor and change clothes. this game gets a 10 out of 10, and you will never want to put it down.