Keith Jarrett plays very melodically and yet his improvisation is quite complex and unrepetitive but it's very melodic. His harmony is very beautiful, not too discordant, pastoral even and certainly in a lot of his solo improvised concerts you get this almost rhapsodic, pastoral come hymnal playing which is very easy on the ear. But the fact that it's improvised makes it exciting because you re never going to hear that particular little melody again unless you keep listening to the record.
I purposely in a way have not memorised any of his stuff but he plays sort of (plays) sort of a mixture of church music and classical music and folk music. It's a collision of all forms of music but they are generally quite accessible. He always errs to the side of conventional harmony and I think that's why he's so successful. He writes great melodies and even when he's playing jazz standards he plays so melodically, it s just beautiful to listen to. Challenging but not abrupt.