I have just flown from the United Airlines LHR Terminal at Heathrow, and on the whole, I had a very smooth process. Terminal 2 is well-organized, clean, and new, with good signage and lots of staff present to assist. Check-in was quick, and security proceeded faster than I had anticipated in a large international airport. I particularly enjoyed the United Club Lounge next to the B gates — soft seating, excellent food, and a peaceful environment to rest up before the flight. Boarding was orderly, and the gate area was generous with plenty of power outlets. The only disadvantage was the excessive walk from security to the gate, but that's typical of Heathrow. Overall, I’d definitely recommend flying from the United Airlines LHR Terminal if you’re heading to the U.S. from London.