I've never been good at shooters in general. I much prefer to run up and beat the crap outta my foes then pew pew em to death. It's strange, I can play first person games like the horror game Condemned, or first person RPGs like Shining in the Darkness and Shin Megami Tensei: Strange Journey. But the moment you put a gun in my hands in that view I become a mess. I more or less spray shots around me in a wide angle then trying to hit a single target.
I guess the hardest part about FPs's are the fact that the view is too claustrophobic for me. Such a narrow view, with enemies flying across the screen every which way, while I'm trying to figure out what is shooting me out of my line of sight. Before I can get my bearings I'm dead, watching my corpse get run over and teabagged by some guy I didn't see in time. Only to respawn and have the same thing happen again and again. I don't know, just never liked them.
In short, no you're not the only one.