Aircraft - new. Engineering - all MEL's get dealt with immediately and tech logs are generally clean, not always sure about the quality of the workmanship though. Training standards - nonexistent, mainly because any training or management pilot who stands up to the boss over any minor thing is immediately sacked and they find a new one. There was 5 different "chief pilot training" appointments in the 3 years I was there. Standard of English is generally low among the trainers, parrot-fashion regurgitation of half-hour-long briefings is encouraged, lateral thinking and problem solving is not. Corruption is an issue as well, the training department is dominated by one particular nationality of pilots who treat it like their little social club, and if you have friends in the right places you can be very very sub standard indeed and sail through your sim checks.
Everyone is on max hours, constant night split duties and min rests, crew are basically a perpetually tired pack of zombies. Staff turnover is highest of all the Gulf airlines, partly because of resignation rate and partly because of the incredible raft of thousands of pages of rules, uniform regulations, notices to crew etc, all of which must be memorized and all of which generally result in termination for the smallest offense. Their CEO is an utter psychopath, AJ looks like Nelson Mandela by comparison.
Basically they're a vanity project by the sheikh - kind of like them "winning"
the football world cup, or buying Harrods - they must be losing billions of dollars per annum but the owners don't really care, they just like seeing the Qatari flag on those big shiny jets.
Their biggest problem is cultural, they think that they can treat safety critical staff like the million other slaves / Bangladeshi building site labourers they have working in their country, there's no difference in their eyes. I know EK and the other not-allowed-to-mention airline are far from perfect, but they're streets ahead of QR in that regard. Hence why virtually no Western professional pilots stay for more than a couple of years.
In my opinion they're an accident waiting to happen, and anyone who forms an "alliance" with them is asking for real trouble.