Delicious visuals, strong storyline, a definite must play.
Hard to really comment on the game to a sufficient level without giving too much of the storyline away for those who have yet to experience the majority of the game, but I'll give it a whirl.
The majority of the game is set in 1191, during the third crusade in the holy land. You play the character Altaïr, an assassin after an artifact that the Knights Templar are searching for. Your initial assassination attempt goes awry, and you're sent back to your master, stripped of your rank, and are tasked with a series of 10 assassinations to regain your rank, equipment and abilities along the way. You start out in the small town of Masyaf, then you move out in the wilderness called Kingdom, from which you eventually get access to the cities of Acre, Damascus and Jerusalem. As you progress through your missions, more areas of the cities are opened up to you.
Your primary assassination missions follow the same recipe each time really - visit the assassin's guild in the town you visit to start your investigation, climb some tall towers to open up more of your map and see some of the tasks you need to carry out (eavesdrop, pickpocket, beat the hell out of someone, and timed flag and assassination runs in later missions), and then once you have a certain number done, you can head back to the guild, tell them of your findings, and off you go to carry out your assassination. Despite the game doing pretty much the same for each of the different assassinations you're tasked with, the cities vary sufficiently in order for it to not become a chore - only things I started to dislike were the sheer number of beggars, drunks and insane people that get in your way in the latter missions. Aside from these, you can go collecting flags in all areas of the game, or seeking out templar knights to kill too, but these are secondary to the main story.
The game's visual style is where it shines the most - the cities are simply breathtaking, and you're introduced to each one with a sweeping view as you approach it. When you've unlocked the city, it's amazing to think that it's a living, breathing city down there - no dodgy looking walls or backdrops, what you see is a city, and you can visit anywhere in it once it's unlocked, and it's all done seamlessly. It's a joy once you scale your first building and start to run, jump and climb around the rooftops, and climbing each of the different lookout points in the city never get boring, especially when you get to climb some of the massive buildings out there, such as the cathedral in Acre. Astounding.
Without giving anything away, the ending of the game surprised me - I expected something a little more... well, not final, but something that felt as if the current game had actually ended? Instead, if you do a bit of digging around, there's a collection of curiosities that tells you that they could go in so many directions with sequels to the game, both forwards and backwards in time. Plenty of options there, so I look forward to where they take the franchise next.