This game seems good on the surface but its not. First off, the combat loses what made the other games good. The challenge to fight 20 enemies without getting hit was awesome. The other games were about getting the perfect timing to make a strike, but now it is just a button bash game. There is still timing involved and the combat is ok, but its not original anymore, just a repetitive mediocre fighting game. It has some cool moves but the combat animations are less quality than some of the original games.
The stealth is the worst its ever been. It sticks to the wall automatically and its hard to move around in cover, not to mention that when you try to go the other way, the camera stays in the same direction.
The driving is clumsy and while its ok when you are going slow, they keep reassuring the horse every 10 seconds which gets annoying quickly.
The gun physics are useless. Sometimes you shoot an enemy 6 times to finish them, where in the beginning it was one shot. Enemies can put their arms up and block bullets with their arms. Even if you get a headshot, the enemy just loses some life and runs over to fight you. It even gets worse if you buy some dlc, because then everytime you start the game up it will spend a minute reminding you what items you have bought, which interferes with bringing up the map.
Its a shame because the story, city design and characters are good. There are also some good features like train robberies, the grappling hook and free running down buildings, but the game is just too poorly designed and badly thought out that its just constantly frustrating. It could have been much better, but as it is, it is the worst assassins creed game yet. (I haven't played Unity though).