Housing allowance is 4500QR! The standard in Doha for expats is 6500QR so if you see it that way its not enough!
If you are a westerner you will need approximately 2000QR extra to live nice. Off course the sky is the limit and you find houses for 18000QR/month as well but for 6-7000QR you will feel comfortable.
If you are used to middle eastern living you will find a big house for 4000QR as well. Different standards, different prices!
We get some extras as well so believe me, you will take home between 20500QR and 22000QR a month as a F/O and around 29000QR/month as captain! They will explain that to you on your interview...
Doha compared to Dubai.....well....lets put it this way. If you are a quiet family orientated guy who likes to go out on trips in nature, who enjoys good food tec you will prefer the little town life of Doha! Doha is changing rapidly and I enjoy it!
Dubai is more hectic, bigger and more modern so if you need to go out a lot etc you will prefer Dubai...
Dubai still is a little more liberal but Doha is catching up...
Hope this helped...