The sitar, and the music played by Shankar, is North Indian. From the stuff I've heard, I actually prefer the South Indian style, which has more fire, I find.
North Indian music is characterized by a very long term swell, so to speak. Like over the course of an hour.
There is zero harmony in any Indian classical music. Only sympathetic tones at best.
There is no fixed pitch system. You can blurt out any tone you want as the "Sa" (or our "do").
OTOH, their stuff might be the most melodic music in the world.
Ravi can tear it up.