First of all you've done a great job and you managed to keep an awesome atmosphere that keeps engaging the viewer.
But I think I know why you don't like this picture.
- composition. See how the character is right in the center of the picture? That's making the composition boring. What you should do is add a little more space in the bottom(cuz she walks that direction) and a little less space on the top. Look at the left and the right sides. They are the same size and both have very similar trees in the corners. You may add more space on the right side. You've done a great job adding a crane and a pond thus breaking the symmetry, but it needs to be even more different.
I think you don't need such a strong perspective on the trees, because this makes her look giant, and I'm not sure if that's the idea.
- colors. there's nothing much wrong with colors because you did a nice job with the pallet, I just wish there would be more reflective lights on the objects. Don't make shadows using black or gray - it makes the picture messy and boring. try adding greenish-gray and yellow and see how it looks. Experiment more.
- organic shapes. crane and the girl look pretty realistic. I can see that she has a skin texture and the bird has a lot of feathers, but I can't say the same thing about grass and trees. This shows that you have little practice with botanic elements. make trees grow in different directions, study them from photos and nature. make grass sorter and add more different colors of it, see how it looks on photos. Same goes for water and all other stuff.
- anatomy. Good job here. I can tell that you draw a lot and know what you're doing. I can advise you to be less stiff and allow more movement for your models. Good thing would be to look at animation sketches because studios like Disney draw realistic people and still give them nice fluent motion. Also try constructively drawing everything that stays under the dress - I can see that you had troubles with torso.
-face. You're right it looks 30+ years old. I personally have no problems with that, but if you want her younger try not using sharp edges and lines, make it lighter and the shadows more fluent. Be careful with drawing nasolabial fold - that's the older peoples trait. Try adding more colors and shades to hair, challenge yourself not to use black on hair next time but still make it realistic.
I hope this helps. I think this peace will be great if you add a few alterations, the idea is still strong and you definitely know what you're doing. Good luck!