I've been flying LHR-ORD-MCO-IAD-LHR routing once a year now for about six years, and whilst the service is a bit rough around the edges, I'd say that they're probably the best of the American legacy carries. They've improved their operations at LHR, because when I first flew with them, queues used to snake around the airport for their flights, yet last two times I've flown with them, I've not been in the queue for more than 15 minutes. Seats are comfortable, food is no better or worse than any other trans-atlantic airline and the inflight entertainment has a range of programmes & films in English as well as foreign languages. Cabin-crews are always friendly, albeit they've been flying for years, but I prefer crews that have substance rather than just another Barbie from the production line. On domestic flights you're usually served a soft drink and maybe thrown a bag of pretzels, and inflight entertainment is available via radio or overhead screens. Flights out of MCO & LAS are all Ted flights, their low-cost airline. Drinks & entertainment are included in the price, service is essentially the same as mainline, but no first class, and the crews tend to be more informal.
I'd definitely fly "the friendly skies" as they're known, certainly better than the old dragons at American. I've never known staff to be quite as rude or service to be so poor as with them.