There is really nothing to compare FPSC to, graphically I'd say it was on par with the earlier MOH games, but it's greatly dependant on you as an artist to put your own style into the game. T3DGM is not even in the same race!, disregard that unless your about 6 years old
. T3DGM can make different types of game, which all use the same generic and somewhat limited engine, FPSC only concearns itself with FPS games, although I imagine there's a lot you can do with it to pull in RPG style elements. People are already trying to develop some great ideas, like melee weapons for instance.
I'm writing a FPS in DBPro, and I have to say it's far from easy, it's damn difficult in fact - however the neat thing about FPSC and DBPro is that they're from the same nest, if you bought FPSC and felt like expanding on your ideas, you could then use your levels in your own custom DBPro game, you can use FPSC then as a springboard. One of the trickiest elements of FPS design is the level system, with FPSC that's done for you along with much more - so it's a great way to get into more advanced projects while still being able to generate games quickly.
Van-B
Put away, those fiery biscuits!