When you're at work, I think the job is great. I've never really had any major complaints.
For me the biggest issue is lifestyle. Unless you are on a fixed roster pattern, planning to do anything in the future becomes a nightmare. I just had to book a weeks annual leave just so I could book a track day I was given for christmas. Its also very hard to keep up with friends and family as plans need to be made a long time in advance, often of days of the week that don't suit most. Once you've missed several 'events' people just stop asking you. Unless your friends are in the industry they find it all very hard to understand.
I still like my job, and am not considering a change, but I'm suprised to say I do fantasize about being back in a nice office, working 0830-1800, home everynight with every weekend off.