To put it simpler, if you want ease in game creation, but trouble in playing.
FPSC is very configuable, but isn't always doing what it is suppose to, the ENGINE is very unstable in some instances, yet not in others. I would suggest buying it for a level creator at least, if you aren't willing to model levels by hand. And if you are really advanced, go with the HL2 Source Engine.
We all have our inner noob. Join the NJL, and have more fun!
I believe society is flawed; our notions on life, on child rearing, stem too far back to be of relevance in this day and time.