I don't know much about his works, of course the Enigma Variations (mostly the Nimrod π) and his cello concerto. I'm not even sure he composed for piano, did he?
I also know him for an orchestral transcription of my beloved Fantasy and Fugue in C minor BWV 537 by Bach which is IMO a pretty tasteless orchestration with a lot of unneeded pomposity and orchestral fireworks that don't suite this deep and eternal masterpiece π