Assassin's Creed goes back to the fundamentals that make video games fun in the first place.
Every time I play this game, it reminds me of why I enjoy playing games in the first place. It's that unidentifiable X factor that drives me to carry on with the game and complete it to t's fullest without worrying about Achievements or my Rank compared to others or any of that other stuff which seems to be the focus so much nowadays. I just have fun every time I pop in this game. Maybe it's the fact that I can climb anything, maybe it's the setting, or maybe it's the fact that it's my first non-shooter game in awhile (excluding GHIII and Forza 2) that I've been attached to. Whatever it is, I encourage you to try it out for yourself and, taking all the reviews into account, you be the judge. Many have critisized it for being repetitive but I believe it is about as repetitive as any other game out there - especially if you're a fan of shooters, like me.
All in all, I'm not going to go in depth as to WHY I like this game so much, just the fact that I DO and that I recommend you to try it for yourself and come to your own conclusion. As for me, it brought back that ever loving X factor that sucked me into games in th first place, before developers had to worry about so much other shallow material to fill up a game disc.