I also have never flown the route myself, but I have relatives that fly it quite often. They have mentioned that the service is excellent, the stewards/stewardesses being especially friendly. In case you're interested, the plane used is a 767-200.
One strange thing is that Malev does not actually get a jetway at JFK. Instead passengers board a hyraulically raised bus, which I affectionately refer to as "the box." This device then takes the pax to the plane.