We traveled from Istanbul to Bulgaria and back, the cost is much cheaper than taking a car for a family, departure and arrival on schedule, on time, we took a small dog with us in a carrier, without problems and surcharges, fast customs clearance, you can buy tickets online for tutu.roo. In Istanbul, at the bus station, you need to check in for a flight at the company's office, seats are already being allocated there. There is Wi-Fi on the bus, but not always (after the Turkish border in Bulgaria it did not work, and we went back from Bulgaria to Turkey - it did not work at all), on the way they give out a glass of water, crackers, make a couple of stops at a cafe for a snack and to the toilet. We were traveling from Bulgaria to the Essenler bus station, the ticket price is cheaper than to the airport, but the bus stopped at the airport.
Turks do not count people at a temporary stop. They do not stop at the stops where they sold tickets (Pomerania).
It was all with me. Be careful and stay close to the bus.