Appears to have been a fuel tank leak from the wing, based on photos and inside passenger video (taken from a seat behind the wing). So after the engine failure resulting in the loss of engine #2, the aircraft appears to have had a fuel leak, leading edge devices not working, loss of power control of engine #1, only half the spoilers deployed on landing (from video), landing gear doors did not retract, and indications of loss of one of the hydraulic systems.
Could it have gotten much worse and still been controllable? I think these passengers were pretty lucky.