The outbound leg from LHR T4 to Doha was on a very old plane (still had cigarette disposal units). My partners' TV screen did not work. Although my screen did work the control panel was permanently embedded in the arm rest - not only did this make it highly awkward to use but the buttons were not programmed to correlate to the places displayed on screen. On the return leg from Doha to LHR the plane was just as bad - plus there were no bags containing earplugs and eye masks left for passengers! The PA system was not working well and kept deafening the passengers with feedback. To top this off there were only 2 loos available for what must have been around 200 economy passengers. I would never choose to fly Qatar again.