Ok, so I am a harsh critic and I admit it. But what does this game do that the predecessors don't? Not much. Ok, there is the training of the brotherhood and the online side but that is not exactly ground breaking stuff is it! The training doesn't even require any great skill on the gamers behalf.
Personally I found that there was too much going on with far too much asked of each button, I would sometimes end up grabbing a horse when I was attempting to interact with an object, thus attracting attention and so on. Then there were the Leonardo's machines missions, these were ok, but again VERY repetitive and the flying machine has almost no control - guys this never worked in part 2 so why persist? And then there are the guild challenges, some of these were just lazy time related chasing about which is boring and lazy on the developers part! (Not to mention, again, repetitive!)
As already stated here the story mode was far too short and the fact you can complete it way before the side missions is terrible game development! Cesare and his Borgia influence were being talked of long after I had killed him!
It's a good game, don't get me wrong, but I found that I lost interest in this pretty quick and I hadn't done that with either of the two games before it. I think the high reviews this game has received can only be down to the age old *pay per review* as opposed to this actually being a real contender for a game of the year. Its worth a purchase but go and get a cheap pre-owned copy and don't bother with paying full price as if you have played the first two there is little new here.