I'll be truthful- some things sound really corny and cliche, but all in all, I think worth a read.
First time I heard about it, I was intrigued. However, the beginning was slow and the style was slightly off for me, so I put it off. Then I read the chapter, RED Interlude, and interest kicked off from there.
Something I have to admire the writer for, is that he/she knows their internet. And TF 2
memes. And has an amazing imagination that manages to incorporate Slenderman, MLP (including Cupcakes and Smooze), Doctor Who (starring the Doctor as Doctor Whooves, River as Minuette, and Jack as Orion), and TF 2
(Painis Cupcakes, Snoipahdiles, Christian Brutal Sniper, hats, and a bazillion other memes) all into the story, and still make sense.
The concept of "Dark" counterparts is a bit too mary-sueish of an idea for me, as well as three additional Elements, but the plot is intriguing enough that I can overlook that. Pyro's a girl, which always bugged me personally, and the pairings are... odd. I mean some, like Demo/Berry Punch kind of make sense, but Soldier/Derpy? Zacora/Spy?
So, some complaints, and the author is clearly not a top-notch writer, but is already better than what I had originally expected, and they clearly take the story seriously. All in all, I would say check it out.