I'm not sure if rhat was a statement, a request for a vote or for feedback, so I'll go with feedback since that's what I'm usually looking for.
Personally I like black and white in general, which is why over half my renders are monochromatic. That said this one looks flat to me. I'm not sure if you're after something realistic (as in trying to emulate reality), photorealistic (as in trying to emulate a photographic result) or NPR (as in trying to be a good image without much care for realism).
So I need to make a few assumptions here. And that's the first of those. Judging from the result, I'd say you're going for a good image, with some stuff added in for a dose of realism but without fussing much about microdetails, SSS or backscattering and how physically correct those are.
So first things first, the flatness. What usually makes a good monochromatic image pop is lighting and detail. Since that's not a portrait and you're not trying to have the light creat the forms of small details like wrinkles, the easiest way to go about this would be contrast. And I'm not talking about cranking a photoshop slider up, but rather the contrast created by the light sources in your scene. Specifically on the girls since the environment is quite interestingly lit. Personally I'd add some strong rim lighting on their left and up to have it silhouette the bodies and make them pop out. Then I'd probably move the fill to have their right side fade into dark, but without becoming one with the environment. I'd probably forgo a main light. As it is now they don't pop from the background enough and the gradient on the bodies is too tame. Don't be afraid to use a second rim to a lower intensity to add definition to their butt cheeks as well (or to keep the definition it already has, which is good.)
Then, I'd work on the composition a bit as it pertains to the camera setup. I don't know if your camera is tilted or the entire scene, but it's distracting. With that, some light grain in post and a bit of boost to the contrast and bloom over in the render options and it would look really good.
If feedback was not your intent, feel free to ignore all that. If it was and you want more, ask me and I'll provide when I'm back from work. But some information about what style and feeling you're going after would help me focus it better. So far I only touched on lighting and was very vague about render settings with minimal info on composition and nothing about materials. But I know I'm probably needlessly making longass comments that probably nobody cares about.
EDIT: Also.. I want the sliders for those asses! Especially the rightmost one. Looks delicious.