I think its somewhat of a human tendancy to complain or think the grass is always greener. That's probably why u hear of some pilots that hate their jobs. Its a great job but it has pros and cons like everything else in life.
Pros: see different places, flying airliners is cool, pay can be very good especially if you are at a major, get more days off than a normal job, don't have to deal with the politics of a normal job, travel benefits
Cons: time away from family, commuting, paying your dues can take awhile (either from the military or a regional), lack of camaraderie (like u have in military)