As a given name, I really dislike it. As a nickname, well, I still dislike it, but not as much.
Frankly, I'm burnt out on Lexi/Lexy/Lexee et al. It seems like Lexi is the nn of choice for every parent choosing Alexandra, Alexis, Alexa, and so on. Add them all together, include the poor girls named just Lexi, and that seems like a lot of kids with the same name.