The new airport in Istanbul is apparently the biggest in the world, and yes it is huge, as I discovered when I arrived on June 24th. Huge, ugly, and in chaos! I was one of many people whose luggage got lost or mislaid, and spent several long and frustrating hours at the airport, until it was found. Being in a wheelchair made it even more difficult, the young Turkish man assisting me was very nice, and did his best for me, but him not speaking English, and me with only about three words of Turkish didn't help us. Istanbul is a major hub airport and literally millions of tourists visit every year, so I was surprised to find so few English-speaking staff, quite the opposite to Athens, where almost everyone spoke at least some English. After arriving much earlier in the night, my luggage and I finally got to the hotel in Sultanahmet just before midnight.
Then when I was leaving Istanbul for home, it was a letdown to find that even though I had booked wheelchair assistance, I had to walk a long way to the luggage check-in before they provided the wheelchair, and frankly, I was in great pain and exhausted due to this.
The assistant was pleasant, but spoke no English, and wound up leaving me in a completely empty departure lounge, no staff and no other passengers more than two hours before my flight, with no way to get a cold drink or use a bathroom.
While I do understand that the airport is new, and teething problems are to be expected, I was very disappointed with my personal experiences there. Hopefully, by the time I visit Istanbul again, they will have sorted themselves out, and provide better customer service.