I like the background. There are a few mistakes with her body, though. Her pinky is like, lolwut. There's something slightly off about the line for the right side of her torso (HER right side), like her torso doesn't line up with her hips the way it should. Her head is a little bit too small, and her tits are a LITTLE uneven. The shading is a bit too subtle, too. I must admit, though, I'm not a fan of more realistic versions of Adventure Time girls, but I'm trying to give you the most honest and constructive review I can. The thing that bugs me the most about this picture is her pelvis. You drew her leg and her butt like she's twisting her body a little, but you didn't give the same perspective on her pubic area. That's just my two cents haha. Also, another thing that I noticed, not just with this pic, but your other stuff, is you use too much linework to show detail in the abdomen. Instead, you should use shading to suggest the detail. A general rule for this that I've picked up on is basically this, only use linework where there are distinct edges, like where the character meets the background, or where one part of the body overlaps another (like where her legs meet her pubic region). Anything else, use shading. This combination of lines AND shading just makes her look airbrushed and doesn't give her the right sort of volume. I hope that I helped you notice a few things that will help you with later drawings. Keep up the good work haha