Hello, I traveled recently on Turkish Airlines LHR Terminal and it was quite nice. Check-in was hassle-free, and counter staff were courteous and professional. I didn't have to stand around too long, and they ensured all was well before sending me to security. The terminal itself was very well-planned and neat with lots of directions to move around. I was especially impressed with the number of shops and restaurants on offer. It was not difficult to find something to do while waiting. Boarding was seamless, and I was impressed with the efficiency of the staff in completing the boarding. Generally, the Turkish Airlines LHR Terminal is well kept and provides a stress-free beginning to your journey. I would highly recommend it to anyone traveling on Turkish Airlines.