Players given the opportunity to playtest the PS3 and Xbox 360 versions of Final Fantasy XIII side-by-side have been reporting the in-game graphics of the Xbox 360 version are noticeably inferior to those of the PS3.
Square Enixs marketing activities, in the form of a touring bus, have given US fans the chance to play both:
From a real person:
I went to the Sunnyvale one today and got to play the 360 version. I am so very disappointed to see the difference in textures and detail of the 360 version vs. the PS3. =( I know its DVD vs. BD, but I didnt think it would be that noticeable. My boyfriend told me its fine if I wanna stick with the 360 version, but hes going for the PS3 one now.
From a game journalist:
Both PS3s and 360s were being used to show off the game, which was great as I was able to see both versions running side-by-side. As expected, the 360 version was noticeably less crisp than its PS3 counterpart, but it still ran nicely.
Additionally, the developers recently made an interesting admission:
It was easy to port to the Xbox. Porting to the PS3 is harder. The PS3 has more processing power but you have to do it properly.
The only difference reported previously was that the movies and sound on the Xbox 360 would be substantially lower quality in order to cram the game onto 3 DVDs in-game graphical differences were said to be absent.
International fans planning to purchase the Xbox version are understandably dismayed by this, although at least it seems to demonstrate the game was not intentionally crippled on the PS3 in order to accommodate the port.
The US release is in March. Taken from sankakucomplex