The quality of life depends on what you make of it. Some people remain miserable no matter how successful their career is, others strive to find happiness in not-so-friendly parts of the world.
But to cut the crap - QR is a pleasant workplace, rosters are reasonable if you bid right (can be done), holiday leave can pretty much be assigned based on your preference. Speaking of the widebody fleet you get to spend reasonable amount of time at home.
People you fly with are 99% professional and friendly if you present cooperative attitude yourself (this is true anywhere you fly really).
As to the job security this is an issue which applies to all carriers in the ME. Stick to the SOPs and company procedures/limitations, be assertive with PIC whenever one wants to break the rules and you should be fine.
The key to your well-being in QR is schooling place for kids and living quarters near it.
You don't want yourself or your wife to spend hours on the road. This is a dangerous place to be so limit your exposure to the minimum required.
Once you find school where your kids will be happy and a house nearby find some friends, so you and your wife have someone to socialize with.
Use staff travel tickets to get out of Doha once in a while if you feel overwhelmed with the beige-coloured environment.
Doha can be a good place to live and great majority of people I fly with share this sentiment.
Bringing your Family here for a day can only give you a brief overview what the place looks like, but you need time to find the right place to live and settle in.
PM me if you have any more specific questions.
Regards
Dom