Lost Girl started out with an interesting premise: superimpose the macro level struggle between various groups of light "faes" and dark "faes" and their human "inferiors", against the micro struggle of one unaligned, newly aware Succubus. The tensions that were presented while the characters' back stories were revealed (along with the racy bi-sexual themes explored week after week) definitely drew in this viewer. And for a while, the weekly introduction of various mythical creatures, along with some twisty character development, provided ample amounts of interest, intrigue, and titillation. However, as often happens with shows that try to be a little too cutting edge, the edge slowly dulled, and the stories lost their punch, and even worse – their relevance.
Part of the reason for this is that while most of the main characters evolved and revealed more and more of themselves as time went on, one of the main characters, Kenzi, remained stuck in some sort of annoying, adolescent time warp. Her never ending stream of childish, over-acted/ADHD behavior began to wear on my nerves like Chinese water torture. For example, in one episode in the third season she's sitting at a bar, blowing bubbles into her beer through a straw -- something you'd expect to see from a 10 year old with a soda at Denny's. And that's just one of way too many examples. She is constantly barging in on others without the slightest regard for the consequences, and without the slightest insight into her actions and their impact on others. And in each and every episode she can't simply address the other characters by their real names, she has to call them by stupid little pet names, like "Bo-Bo" (for Bo) and "Trickster" (for Trick), etc. She simply never grew or evolved at any point during the show's first 3 years, and I found myself hoping that the powers that be -- be they light or dark or Neapolitan -- would simply write her out of the series. (It's hard to tell if it's the fault of the actress, the writers, or the director(s). But I suspect it's a combination of all three.)
Another reason Lost Girl got so lost is that not unlike other series that have followed similar courses, it veered off into sophomoric humor that dulled the original cutting edge premise into dust. The strength of the shows' anti-hero characters got diluted by unnecessary silliness masquerading as hip humor. (Vex, the impotent masochistic eye liner maven Mesmer comes painfully to mind.)
Finally, when a show attempts to embark upon the slippery slope of amoral morality, it better have some serious substance to back it up. That's where Lost Girl really drops the ball. It devolves into little more than a soft core porn escape into situational ethics, with some pop psychology/psychobabble tossed in for good measure, all set against a back drop of an off the wall lesbian/bi-sexual Succubus situational comedy. Toss in the fact that Anna Silk, while very beautiful for a 40 year old, is, nonetheless, 40 years old, and as others have pointed out, she's a rather hard looking 40 year old at that. (And I don't think the raccoon-looking eye makeup helped much in that regard.) So added up, it's really just a recipe for disaster in anybody's book, and as a result, Lost Girl lost its way and dissolved into a sloppy gooey mess as surely as some of the humans in the Faes Wide Shut episode.