I've played a bit over a third of the main storyline now. Tonight, I started trying to quit the game at about 11. At around 1:30 AM, I succeeded. I'm a sucker for owning an expansive world like this. I've gotten much better at the mechanics. After 15-20 hours of running and jumping all over rooftops, walls and alleys, it's finally getting easy. This game rewards practice, and that also includes combat.
There are so many actions that are possible. There are 3 speed ranges for moving on foot, and another 3 for a horse. That is, the stick is analog, so you get a variable speed range that way. Then you can hold down the high-profile trigger and go into a jog or trot range, and the A button changes meaning from blend to sprint or gallop range under high profile. All actions happen faster in high-profile mode, and you attract more attention. When in a sword fight, this trigger then enables a defensive mode, and you can perform several different moves in response to an attack, like block, break a hold, and counter-attack. The face buttons correspond to different parts of the body. X and B are the hands, with X being the weapon hand and B being the free hand. A is legs/feet, and Y is head. Which action these body parts take depends on whether you're fighting or not, and on whether you're in low-profile or high-profile mode. There are special attacks you can make with the sword, depending on how long you hold the X button, and whether you time a 2nd tap on X at the right time, when the sword hits the enemy.
In short, there's a lot of depth in the gameplay. I didn't even touch on all the acrobatics finesse. They did a fantastic job of giving you a lot of control, but it does take practice to get good at it. Frantic button mashing won't do.
The environments are fabulous. The cities are functional works of art, and they are huge. Figuring out how to navigate it all is entertainment enough by itself. Add all the populace, the decent AI, the long dual story, the professional voice acting, and the good atmospheric music which changes with locale and the urgency of your situation, and the result is magic. Repetition? Well, yeah. Hey, just stop saving citizens and doing more than 2 investigations per assassination if it bothers you. Don't collect flags. Don't scale every eagle-marked viewpoint. These things are mostly optional, although they will increase your lifeline, and fill in the map. (Think leveling up in RPGs.) The flags give you nothing other than achievements. Personally, I love doing it all. I'm in no rush. This is a game to fill weeks of your time, not a couple of days. There's too much here to plow a straight line to the end.