I can only comment on my experience at Qr as Dec on the triple, but it has been more pleasant than described by some.
Housing is expensive..especially if looking for a large villa for family. Currently I believe everyone at Qr is given company housing although in the past it hasn't always been the case.
If you have school aged children it is a problem finding space and the schools are getting very expensive.
The roads and driving here.....like most places in Middle East
As far as the training....I was not type rated and did full course. The ground portion was stretched out for 6 weeks...a little long but nice pace.
The FTD/ sim portion of the training was in my opinion done very well and thorough. Of course you need to show up prepared but it was overall very good.
The line training was always quite professional....I have many an instructor say we need to cover this but it is not a test ...if you don't know it we need to talk about it. I had over 10 different training captains and found them all top notch and professional. Training is never fun and always stressful in my opinion but this was better than most of my experiences from USA.
The flying as normal line pilot has been very good.....the triple 7 has better roster than say the 320 and I can't comment on the training..especially for second officers. I do know many second officers have had quite a back up in their training, often waiting up to a year.
It is a big decision to pack up and move your family to another country...do your research definitely. Expect some things to not go as smooth as possible and Qatar is expanding rapidly so there are growing pains.
Again I can't comment on living here long term.....it is always difficult to be away from one's own country so that adds stress to the job, but overall, either I was lucky or the situation is improving slowly.