Teenagers might enjoy it, but don't believe the 9.0 rating. It really is not worth 60$+ tax. It's a rental.
This game is kind of a cross between Grand Theft Auto and Spider-Man games. It sort of has an open world, although much of it isn't available to you until the end of the game, but it's okay, because there isn't anything to do but repetitive, mind-numbing, and extremely stupid side missions. You can skip some but the main missions in each town requires you to do several. Boring, I'd like to emphasize boring... because of how totally annoyed I am with this game. It's so boring, it's like talking to your Mom about bowel movements. It's so boring that it's like having to watch your little sister in a school play at elementary school. It's really really boring. Imagine that your girlfriend dropped a hundred onions in front of you and said, chop them all the same way. That's what Assassin's Creed is all about.
The world is ridiculously huge, but pointless. There is no reason to even go to 90% of it. It all looks the same, all the people do the same thing, and the missions are all the same. There is something you can do in the gigantic world of repetition... collect lots and lots of flags! Oh boy! As soon as I realized how every town is exactly the same, I forgot about the flags because all they meant were achievment points, and only 10, so that was stupid to me.
Next, you are supposed to be an assassin, but forget about stealth. It's an advanced hack and slash game with an annoying targetting system, and hope that you are in an open area when you are fighting 3+ guards. By the way, it's always guards, always. Unless you botched a a joke of pickpocketting job (you can only pickpocket chosen characters for knives), it's guards. This is the only thing I enjoyed about the game because the fighting gameplay is pretty decent. Still though it gets really boring after a few hours, it's especially annoying because most of the time you didn't even want to fight. There isn't much of a way to stealthfully kill a person because every city and area takes place during the day. Even if you travel for hours and hours it's still daytime. Which wouldn't be a big deal if they didn't call this Assassin's Creed. It should be Samurai Creed. Because it feels like watching an old samurai movie when playing. You're ONLY satisfaction of killing someone without any one knowing instantly, is on the rooftops and you have to be lucky. Almost every situation where you kill someone winds up with 3-5 guards who all do the same moves, say the same things, and die the same way.
So basically the open world and the idea of an assassin has completely shed itself from the game within two hours of playing. What you wind up with is a huge but unnessesary world that looks breathtaking, while the gameplay is good at first, it gets boring after an hour or two. In every town you will save a citizen, eavesdrop, interrogate (this is in between the 6-12 viewpoint climbs that reveal the map locations of every side missions which is also very annoying), or pickpocket. Later on you'll have to get some flags within the alotted time, or assassinate some schmucks without alerting guards which can be WAY too annoying to even want to do over and over because if you fail you are punished with the same dialogue that you can not skip, and it is very easy to fail. As if the side missions aren't annoying, the main missions are just as bad, same basic elements, you go to a town, talk to the guy affiliated with your creed, do a few annoying side missions, then you get to go watch the bad guy kill a person (almost everytime), in some fashion then wander off. After that you have to get by lots of guards, if you want to try and assassinate the main bad guy, good luck. It's close to impossible for most of them. They will most likely see you before you can ever get close enough to attack. Every so called boss (who are the same as guards, no special moves but more annoying because usually they run through the city so you can fight more guards), is the same as the next one.
The story might have been interesting but I couldn't follow it because it was really anoying to listen to them talk to each other. The "Assassin" you play as has a voice that is gutwrenching. He sounds like a monotone snob, he's completely annoying. That's your Assassin?! Say it ain't so. It's okay though because the end of the story doesn't give you any satisfaction, it makes no sense, and it's very frustrating. Finally leaving you with this feeling that you shouldn't have even played the game at all, there is no meaning, no moral, nothing of interest, and very typical. It's kind of a Matrix style story with two annoying people running the machine. In between the guts of the game, you are taken out of the game world and brought into "reality" where you can listen to an old man whine, and a girl obviously take your side. When walking around in this part of the game that's all you do. Walk and listen to the other main characters. There is a part where you take a couple of pens... but nothing ever comes of it. Also these two characters have a computer, which you can just read their email and figure out whats going on but you can't do anything else but go to sleep. That is if you can place your character in the right spot to hit the button that allows him to interact... you may have to walk back and forth until it pops up on the screen.
While this game is mostly nonsense, it does have good graphics and gameplay. You do get some enjoyment out of running across rooftops and climbing towers, and killing people. Once that cool factor goes away, you realize it is definitely not an assassin game, because you don't ever assassinate anyone. You'll run in or climb in trying but wind up being seen and you murder them all and the whole town knows, it really isn't much of an open world game either until you complete it... but then there really isn't anything to do but collect flags and kill people. The best parts of Assassin's Creed is near the end when you have all the weapons and moves available to you, but it's because it actually has some scripted events. The fighting parts of the game really feel like watching an old Samurai movie, where the main Samurai sits patiently waiting for an attack, and then pulling some amazing counter in the midst of twenty or thirty foes.
In the end, it's not a 9.0 game, it's not worth 60$, it's not what it says it is. It's just a really pretty world with nice controls. After that it's no fun anymore. Unless you don't mind just running across rooftops, killing people, and wandering around a totally unnessesarily huge world like most of these people who rated it 9 and 10.
It's a mindless, meaningless, repetitive game.