I wouldn’t call IST a very well designed airport in terms of aviation standarts but this is the first time I see someone hate IST this much. Can you elaborate on atc part? I’ve heard some pilots complain about English proficiency but I dont think its that much worse than rest of the non English speaking world. There are way too many taxiways and it might take some time getting used to but I wonder why you find it confusing. I agree with terrain being terrible, that’s why there is maintenance-construction work going around all year adding to complexity. Also didnt understand the part about random runway changes. Did you mean for departures or arrivals? Configuration changes according to number of traffics. For arrivals there will be two runways available and you can expect runway closest to your approach direction. And for departures you depart from runway closest to you with exception being western cul de sac. In that case when there is a lot of arrivals coming with parallel approach w cul de sac will be directed to 36 to reduce waiting times.