This is an example of how a relatively small change can make a really big difference in how a game's mechanics are perceived.
From the first time I saw Assassin's Creed, I knew I would have to play it. On top of being done by the same team (or as much of it as possible, I suppose) that did Prince of Persia: The Sands of Time (one of my favorite games ever), the mechanics and scope that they described were extraordinary.
Parkour, dynamic crowds in an open world, "social stealth," espionage and free-form assassinations... wow. This game has everything! And indeed, it did. The parkour, in particular, is extraordinary. Controlling the main character is a pleasure, and the way he runs through the city is nothing short of revolutionary. The game's other individual mechanics, from blending in with monks to simply listening in on a conversation are also well-executed and entertaining. The story is interesting and well-told, and that's as much as I can say about that without getting too spoiler-y.
However, Assassin's Creed suffers from one major problem, and it's bad enough that it is, I believe, the cause of all the "hate it" reviews on the "love it or hate it" spectrum:
Repetition. Or rather, the fact that the game *feels* repetitive, not that it necessarily is any more repetitive than any other game.
Calling the game repetitive feels really unfair, having played through the entire game. The game consists, essentially, of nine individual assassinations. For each assassination, you have to scout your target, learn where they're going to be, what the general populace thinks of them, and what the best way to get close to them is. Every assassination has potentially an identical flow: find local assassin's bureau, find a number of "viewponts" (tall locations from which to survey the surrounding area) to find the "scouting" objectives, perform a number of "scouting" objectives (which include things like pickpocketing, listening in on conversations, interrogating people, and performing random fetch quests), then carrying out the actual assassination.
This is actually a really wide variety of stuff to do, and the fact of the matter is that you can perform a relatively minimal number of these tasks in whatever manner you wish. You don't have to do every single one - it's up to you how you want to scout the target. The problem is that each task is highlighted on the player's map once it's found via a "viewpoint", and all you have to do is go to the area on the map, perform the task, and be done.
This is a really, really big problem, because fundamentally, that simplicity and straightforwardness work against the core mechanics of the game.
The game is about freedom of movement and observation. The best parts of Assassin's Creed are when you are running around making really quick decisions on the fly, based on where you are and a quick analysis of your surroundings.
Unfortunately, the highlighted tasks on the minimap force the player to concentrate on the minimap, and not on their surroundings.
That the player knows everything that they have to do without looking at their surroundings is a really big problem. It completely breaks the illusion that the people are behaving autonomously - all their actions are predetermined, and the player is told by the minimap that they'll happen on cue.
When the player gets to the highlighted spot, the conversation the player needs to overhear starts, or the NPC with the item you need to pickpocket starts in a specific location and walks off - always perfectly on cue. Obviously, for a game, you need things to be controlled and communicated to the players in some way, but this still sucks.
Thing is, the trigger for the behaviour *still* happens, even if you don't have the objective on the map. When you happen across one of these things and recognize it in the world, it's much, much more immersive.
Best of all, it's still recognizable. If there had been a slightly different HUD element that kept the player's focus on the world, that forced the player to watch the crowd instead of the minimap, the entire atmosphere of the game would be totally different. Even better, if the animations and crowd reactions were distinct enough to draw your attention to the events, you could conceivably do it without HUD elements, or restricted to the existing in-game HUD elements that are used to highlight characters.
The second problem with the minimap is that it shows *all* the local events. When you present a gamer with a variety of events and they're all undifferentiated, it places the same value on them all. If you have to complete one objective, you have to complete them all. Again, this works against the concept of a world that feels real. In a real world, you never have five objectives that all have the same basic value. Because everything feels the same, there's no real way or REASON for players to choose one objective over another other than what they want to do.
That's not the right kind of choice to present to a player, again, because it destroys the illusion that the world is a living place. If the player can say, "During every assassination, I want to do only the pickpocketing objectives," and they can, it's not a real world with real people in it. In a real world, the assassin has to find the opportunity and utilize it. In this game, they present you with every opportunity, and it's up to the player to take their pick.
Again, the weird thing is that this doesn't make the game any better - it's one of the main reasons the game feels so repetitive. Not only is each option present in each assassination, each of those objectives is essentially free of context. They're simply small objectives that open a larger objective. If the objectives were put into a larger context, if they weren't all there at the same time, and it wasn't solely up to the player to choose, these things could be woven into the larger objective in a stronger way.
The context, then, would make the objectives themselves feel less isolated. A pickpocket objective where you're pickpocketing a specific person in a specific place is interesting - but because of the choice you're given, and how isolated each mission feels, each pickpocket mission feels basically identical.
Assassin's Creed is fundamentally an extraordinary game. Its movement mechanics are utterly unparalleled, and the world feels really well-defined and real. The story is interesting and the mechanics are diverse and varied. The problem really lies in the details of the presentation - by giving the players choice but stripping away the reasons one would actually make a choice, the developers missed a great opportunity to take a collection of excellent mechanics and turn them into something greater than the sum of their parts.