If you're a fan of past God of War games you will love God of War: Ascension, it's an amazing game that I'd recommend to any fans of the series or genre.
The graphics are the best on consoles by a large margin. The art-style and wide colour palette exemplify the amazing technical graphics. It just looks beautiful.
The gameplay is fast, fun and exciting. Plenty of upgrades, magic, world weapons and an element system keep combat fun and varied.
The sound is brilliant with an amazing OST by Tyler Bates and a first class voice cast.
The story is great and seeing the human side of Kratos is interesting. I don't want to say much and risk spoiling it, it becomes even clearer/better on a second play-through.
The multiplayer is incredibly fun, it's good enough to be a standalone game.
So yes, if you have a PS3 and you're over 18 years old you MUST buy this game, if you're a newcomer to the series I also highly recommend trying both HD collections and God of War III, all are such amazing games and can be bought brand new for a very good price nowadays.