We were pleasantly surprised with Turkish Airlines, although this was about 3 yrs ago... the food was amazing (and we are very picky eaters) .... the people were stinky on the airplane, and on mass transit around Istanbul. Istanbul is beautiful at night and the people were pretty friendly. A few were pushy but we were able to escape them pretty easily. I'm not sure that I would travel through there now, with all the political/terrorism stuff going on, but it was fine a few years ago. We were able to get around pretty easily, not speaking any Turkish. Picked up one of those pocket guides to the city and had a good day seeing most of the top 10 sites, etc.
Check-in/Customs with turkish airlines was difficult. if you are not Turkish, the Turkish Airlines gate check-in employees will likely pull you for secondary screening (Racial profiling?) and give you a hard line of questioning. Saw it happen to most American-looking types on our flight from Istanbul back to the U.S. Had a long layover in the airport, as did quite a few people we saw there. Many large groups just sleeping along the walls, etc. But the concourses are wide and long so there is plenty of room. We felt safe at the time, and everything was well-lit... lots of food options, etc.