Just a year after the release of the new champion Naafiri, the League of Legends community criticized her design, making her the least popular character in the game's entire history. One player conducted an in-depth analysis of Naafiri's issues in a longread format. 

According to the author, the developers' goals in creating Naafiri were flawed. The studio released the hero with the idea of a "simple assassin for beginners", but it didn't work out.

NaafiriImage: reddit.comThe author of the investigation believes that Riot Games didn't continue developing the champion after release, citing the lower popularity of "monster" characters. Many players would have preferred to see Naafiri in the jungle role to boost her popularity among a portion of the audience.

I can understand why not let her jungle at the first month or two as to push her identity as a mid laner or solo laner but once the dust settled down and mid laners voted with their pickrate that they don't want to play this absolutely boring kit, Riot should have immediately given some jungle ratios and see how she would fare in the jungle. 
bodynasr

According to the user, the main complaint about Naafiri is her contradictory gameplay: the character more closely resembles a skirmisher rather than an assassin, which she was intended to be. Her kit of abilities is uninteresting and offers no room for mastery. Additionally, the heroine's story hardly connects to the gameplay at all.

Main image: leagueoflegends.com