This can count an "Above Good" picture!
It doesn't mean its suck horrendous cherries, because it certainly doesn't, but it can go for some reworking! When or if you consider a "Slender Girl #4" :D

-The Color: The Slender lore is a very black and white world (Think of it in terms of Limbo) Although you do have most of this piece in black and white, the only two things with color is the grass and the eyes. Though i have no problem with this, you can definitely improve on this by rearranging on which and what object or parts should have the emphasis on color. (If you to hear my opinion, which i know you don't, i think the only part that should have color is the big ol' red eye you have as the main grabber of this drawing)
-The Quality: To the point, if you're going for a real slender, the big guy doesn't have a face (Though this is more of a fan art-ish piece right?) Just by looking at this, it looks like the body itself was the object you put the most effort on. Though it's an O.K thing to do, considering it's what we're supposed to be attracted to, some improvement can still done. Re-working on the appendages coming out of this Slender is definitely something you should be doing, but besides that, the clothing seem to reflect off or become transparent to that of what our Snow White Slender is. This can mean: 1. Slender Girl #3 is glowing and her apparel is reflecting that light off it 2. The background lighting, which to be honest is a blobby water-colored slap on, is reflecting off our Slender Girl. Also what personally bugs me a little is this very opposite feeling i have for the character you have here
(She has this smile, so she's good, but then she has this red eye, meaning she's evil, or whaa..)
The backround can use some more detail! Maybe not going all out on it, but more-so just a bit more detail so that we can see the bark on some tree or the blades of grass on the floor waving around.

Besides all this, being honest here, it's not a bad character! I've seen many fusions with Slender and Jeff the Killer in my days that i just want to break my screen in disappointment! Fan art is neat-o when there's originality aboard! Though i've seen Slender for a big amount of unattainable time this is a good refresh from it all!

GG U WIN ART, 2 KAWAII 4 M33333333 C:>