We recently flew from Los Angeles to London and weren't very impressed with American Airlines. Firstly, in the airport the whole check-in process was long and confusing. The staff were unhelpful and didn't seem to know what was going on themselves. Terminal 4 (which seemed to only be for American Airlines) was dreadful, way too small for the number of people. The number of places to eat were severely limited and way over priced. We walked to the nearby terminal which had loads of shops and restaurants.
The plane itself was fairly cramped and this showed, especially after our outbound flight was British Airways which was much better. The food on the flight was average. We were given complimentary drinks occasionally but no snacks, which I would have expected for an 11 hour flight.
Would likely avoid AA in future.