With me, unless an FPS has something really different to offer (non-graphical, mind you), I honestly don't pay any attention to them. I've always been very picky about them, and only a handful have ever really made me love them almost instantly (Doom II, Half-Life, Metroid Prime [leave your FPS/FPA arguments at the schoolhouse--I'm just talking about games that are set in the first person, simply]). I'll give XIII a look, but I haven't kept up with it enough to really have an opinion on it. Looks "interesting."