It looks like they learned a lot from their mistakes in the first game. Here are a few key changes:
- 16 mission types (and they removed a couple of the lamer types from the first game)
- one huge open world
- swim on the surface and underwater (this can play into your assassinations as well as getaways)
- use all weapons in the environment, including anything enemies are using
- more seamless, open flow to the game instead of the fairly rigid structure the first game used repeatedly
- two assassin blades that you will automatically use when appropriate (no need to ever equip them now)
It sounds really, really promising.