Not with a toddler, but we did some long hauls on Turkish with a preschooler this past winter. Very impressed both with the airline in general and with their service for young kids. He got a very nice kids' meal plus a travel pack with headphones, coloring books and some toys. Also, the meals in general were the best food I've had on an airline in a very long time.
Can't speak to the specific car seat issue, sorry.