It's easy, formulaic and repetitive, but it will suck you in if you approach it with the right mindset.
First off, we've got the setting. Since the game is labeled as a 'historic action adventure', you can expect some historically accurate elements. The action takes place during the Third Crusade (1189-1192, the game itself takes place in 1191). The main character, Altair, is a member of a sect of assassins that are working behind the scenes to put an end to the conflict. The assassins in the game are actually inspired by the order of the Hashashiyyin, which existed around the time of the Third Crusade. There is however a sci-fi twist, which actually works nicely. So there are two story threads, but both are related to events from the Third Crusade. The game shifts focus between the two threads on a few occasions, making the whole thing feel a bit fractured, but it's a good story overall.
The main strength of Assassin's Creed however is the gameworld. I can honestly say that this is the best looking game I've ever seen. And I'm not talking about how photorealistic it is or how much bloom it has, but just how authentic it all looks and feels. The size, the architecture, the streets teeming with people going about their business, the huge number of details... it's all beautiful and it really helps you feel like you're there. You'll get to visit three major cities (Acre, Damascus and Jerusalem) plus a few smaller locations so you can look forward to plenty of exploration.
For a game that looks this good it would have been a shame if the sound was not up to the challenge. But it is. Everything from voice acting to sound effects and music fits perfectly. It would have been nice to have a larger number of musical themes, to avoid repetition, but what the game has is of good quality. Jesper Kyd (the man who did the chilling score for Hitman: Contracts) delivered once more.
Right, so Assassin's Creed looks and sounds great. But what of the gameplay? Well, here's where things get ugly. If you do one assassination mission, you basically do all of them. What I mean is they all take place in the same manner. It's like a ritual. First you travel to the city district where the target is and report to the assassins bureau, then you climb atop a number of view-points scattered about and you observe the city streets. Your map gets scribed with all sorts of info, like good places to eavesdrop or the location of informers that will provide you with information in exchange for performing small favors. There are a few optional goals too, like helping citizens in distress, which turn into friendlies that will aid you escape if you're being chased. But for the most part, the ritual is the same. After you gather sufficient information you report back to the assassin's bureau leader, who gives you the green light to take down your target. Now take this ritual, do it 9 times (there are 9 targets) and you've not only got a formulaic experience, but also a repetitive one. Although, truth be told, each assassination plays out differently so that adds a bit of variety.
But repetitiveness is not the biggest issue. The game is also easy so you don't really get challenged along the way. The worst part is the combat, which is made very easy by overpowered combos that enable you to take on even 20 enemies at once. And once you see how easy it is to take them down through straightforward combat you'll also stop being careful and just tank your way through. Which also breaks the game's spell, exposing Assassin's Creed as just another one of those really accessible 'next-gen' games that don't require any brain power or skill.
Thankfully, the gameworld is pretty open and you have the option to choose between different play styles. You don't have to tank your way through - you can avoid combat in a lot of situations, you don't have to climb those view-points and have your map automatically scribed - you can just go explore the streets and find informers and good eavesdropping spots yourself. Basically, you have the option to do it the proverbial hard way. And while this doesn't excuse the flawed gameplay, it does provides a somewhat better experience. But again, when you're not being penalized for being sloppy it's only normal to choose the easy way out.
It's a shame. What a masterpiece this game could have been! It can be such an immersing experience since it's one of the very few games that delivers on the 'living, breathing gameworld' part. But thanks to the accessible, formulaic gameplay, the spell will inevitably be broken at some point. It's a real shame. I don't regret getting this game however, it was decent fun to run around the busy streets and rooftops of Acre, Damasc and Jerusalem. At least Assassin's Creed tried to do something new and I must admit that it left its mark on me, both good and bad, which is better than bland across the board. Get it if what you've read sounds appealing to you, just expect to feel some measure of disappointment too, no matter how much you love the idea of being a master assassin. It's one of those love-hate games.