I hope you won't think it's crass of me to say that that is a perfect ass!
The picture as a whole is a wonderful piece of erotic art. I love how the wave of her hair echos the curves of the backdrop. And your use of contrast is masterful. I noticed how none of the various tones in the backdrop really match the tone of the model's skin, which draw's the viewer's attention on to her. (As if that gorgeous deriere wasn't enough incentive! )
It's funny because a lot of "artistic" nudes posted here on Deviant Art isn't exactly artistic for me. They lack concept. Some have captivating eyes or striking poses but nothing else. This, on the other hand is really good, especially with the other curves in the background. <3 This deserves the daily deviation. Congrats! You deserve it.
<rant>lately i've been reporting alot in that section cause it's like here's my penis boob butt vagina horrible cell phone shots just taken in someones bedroom THIS is actually an artistic piece not the usually porn sorta crap </rant>
This might sound odd, but I love how the tiny little gap between her thighs creates a heart in white. The contrast in this shot is wonderful; this couldn't have been done effectively in color. Wonderful work.