I was playing the 24th caprice and It really is one of those songs that can't really be played with a metronome, at least not all the time. Don't get me wrong some parts you really need to build speed with a metronome but some parts he keeps slowing up and down so its more in free time. I was listening to the Jason Becker Version but they all kind something similar. What do you guys think is the hardest part?
all the fast arpeggios change... they creep me out, but i'm still working in it

and those weird rythm changes parts are because they're played A capriccio or A piaccere (something like Ad libitum)