I recently flew with Qatar Airways in an intercontinental flight from Doha to Miami (more than 15 hours long flight!). The aircraft was an Airbus 350, therefore relatively new. Everything was perfectly working, clean and operative. In-flight entertainment was not bad, even if the choice of movies was not so wide (i.e.: the "I.C.E." entertainment service from Emirates is way better). ALL the flight attendant were available, nice and polite. The food is not the best ever seen but I cannot complain. I had a special meal and they called by name, which is a nice thing that makes you feel more under consideration. Restrooms are clean by the crew after every use.
I'd definitely fly with Qatar again (especially on new airplanes...).