A great game that could be perfect with a few ajustements.
The missions are great, very fun to do, and I personaly like the caracter and villa's improvements, because the game envolves as you progress the game.
There's a lot of things that I like in the game that's already been told, but I think Ezio (main character), could have stealh modes like in Hitman or Splinter Cell.
You should be able to hide in the shadows, or being more undetectable at night. You should be able to sneak in the walls, peek in the corners, crouch in the lower walls.
As you can change the colour of you outfit, some colours should be best in being unnoticed in some environments than in others.
The best your armor, the more health you get, but metal armor is heavy, shouldn't that be a problem in climbing, running and swimming?
Other thing that I think that's a little annoying is that sometimes the Wanted posters are in higher places, so you have to climb to rip them, but shouldn't that be in places where people could see?
However, it's a very good game, very addictive and with many many playing hours. If you like GTA 4 and Assassin's Creed, this is going to be the best game in the genre you played.