Ok, so having played every Final Fantasy from 7 onwards I have mixed feelings about XIII.
Battle system (partly)
No Gil after battles
Story play time
So the positives are definitely the graphics and the characters with good textures and nice looking environments. The battle system is fast and slick but its a shame there isn't more control over the AI. Just having an option to pre program how the other 2 characters perform in battle would be very helpful and more fun, instead of just having the computer decide what to cast or how to attack. The story is good but a bit too short for my liking and I didnt think the boss fights were challenging enough in the story. The missions had much harder bosses and that is mainly post-game play.
The negatives were really frustrating for me and held the game back in my opinion. The main issues are regarding Gil (money) and the farming that goes with it to acquire new weapons, upgrades and accessories. The problem is that there is NO gil after battles, only a few 'spoil' drops. This means that you will be spending about 20 hours farming Adamantoise, Soldiers, Long Gui and Sacrifice's while running around corridors that are way too long. Meaning that post story the game gets very repetitive and rather dull which is a shame.
My tips if you are interested in this game buy it and use online guides and tips sites to aid you, since getting the trophies can hinge on one small mistake you want to make sure you don't miss a treasure sphere or sell the wrong item. Oh and create multiple saves as the upgrading of weapons can be really time consuming.
Overall i'd give the game 8/10. With a few alterations they could have made this a really classic but it just falls short in some areas. It's a nice change of pace from MW2 though so yeah, go buy it and check out Fangs abs lol