between one and a half and two hours and it's usually a bit bumpy as you come in to land at Palma, as you fly in over a mountainy bit, then a plain covered in windmills. Always lots of thermals.
The scheduled duration (based on easyJet's timetable) is 2 hours 15 minutes. Like all airline timetables, that's based upon the time from when the pilot receives clearance to 'push back' from the departure gate, to the time of arrival at the airport gate in Palma. As Kim's post suggests, the actual flying time will be a little under 2 hours.