I lived in Doha for 5 years. Is a good place to live (for family). We were very happy!
QR is a great airline and opportunities come fast for upgrades or fleet transfers. However is a ONE MAN SHOW company. The CEO pretends to play GOD and he decides everything in the company so better be low profile. A warning letter is very easy to get and it will mark you in the company... And if he doesn't like you or you have a problem is better to look for another job.
Other than that I have many friends who have succeed and have a brilliant career in QR.
All the best to all of you...