Miles Davis Newbe Question

Miles Davis had several 'periods' and depending on what sort of Jazz you best like:
Kind of Blue: the classic Miles
Sketches of Spain: more classic
Bitches Brew: Miles on LSD

I'd also recommend a live recording as well, such as, "In Person Friday and Saturday Nights at the Blackhawk, Complete". Great music, easily accessible, and terrific sonics.

Miles was a complicated artist and his career was long. If you want to learn
about his music, go to Allmusic.com and do an artist search. Spend a little time
checking out the discography section for a good overview of his music. I agree
with Elizabeth as far as "Miles Big Three" goes. The big change in
Miles music starts in the mid sixties, around the time of the album
"E.S.P." He was feeling restless and wanted to make music more
connected with the cultural changes going on. He morphed into a quite different
musician as the sixties progressed.