Elektra is one of the most iconic characters in the Daredevil mythology and so, after the show's first season got so much right, it seemed that season 2 would do a terrific job of adapting the ninja assassin. As it turns out, things didn't come off exactly as hoped.
Elodie Yung was a strong choice for the character, and the material about her bringing out Matt Murdock's wild side worked well. When things turn towards the Black Sky storyline, however, the character falls apart. Just as with everything to do with the Hand, it's tough to get invested in the idea of Elektra as a prophecised chosen one for the evil organisation and it just feels like an unnecessary over-complication of a good character.
Things only get more convoluted in The Defenders, where Elektra isn't really Elektra anymore - except she kind of is. Oh, and she now has a heap of superpowers that are never explained and disappear halfway through the series. There's still a way to salvage the character, but it's probably for the best if she just stays away for a while.