My favourite lens of the entire EOS system. Wonderful contrast, sharp enough, light, reasonably small, very well built, great AF, and relatively affordable (for an L lens). I also love how it focuses really close (0.28m/11")- try that with an RF or with the average 24/28-70/80mm SLR lens.
Superb lens, excellent value for money.
Only minus is indeed the distortion, it bugs me now and then for horizons- nothing terrible though.