Evelynn is my most disliked champion. Am I the only one?
The reason is, simply put, that she's boring, boring, boring. The only thing she has got for her is being a sexy chick, the overused trope of the "black widow".
Except, there's many other characters in League who play the same exact trope..... but with something more interesting. LeBlanc, femme fatale with illusions. Elise, femme fatale who's also a spider. Cassiopeia, femme fatale who's also a snake. Katarina, femme fatale who's a stout assassin.
Evelynn is just another femme fatale...... but doesn't have anything else.
. But thats because of gameplay, not the character