As a current FAIP, I can say I was pissed for months about my job, as are many of the others I know. Of everyone I know though, not one of us would let hating our jobs affect our performance. It's not the student's fault I hate my job, and the military isn't about liking what you do. You do your best because it's your job to perform to the best of your abilities at all times.
Can it be a screw job? Sure. Most Faips are minimum top half, most likely top third. As an IP, I've been pissed at the way I've seen some students picked to FAIP. When assignment time comes in three years, whatever you get WILL AT THE VERY BEST, be the same thing you could have gotten three years ago. (Unless something new like the 767 pops out).
Can it be a totally excellent experience? Sure. A married guy can spend time at home. I on the other hand am so jealous of my friends in the desert and other parts of the world. As a heavy guy, it is a great career move regardless of whether you want career air force or to get out. Tons of IP hours now means little copilot time later. It does, however, force you (somewhat) into two consecutive operational tours, which might burn you out.
In the end, it doesn't matter what you want... you can be pissed, but it's needs of the Air Force, as little solace as that is, and you gotta do your job.
I could write a book on this though. Just my 4 cents worth.
