This piece looks great! i love the shading and the reflections on the legs from the water, the pose isn't stiff and look really fantastic.
The background is a good start! i suggest the use of a two point (or higher depending on the context of your image) grid. This will make your background have a sense of depth, as i can see the tops of your buildings seem to not follow any horizon line with breaks the immersion that your character is within a setting. Perspective grids are essential in drawings with backgrounds so everything looks correct and realistic in propitiation, or it tends to end up all skewey and misaligned. I also noticed that the ladder seems to bend against the edge of the pool in a way that looks impossible, or that it would be slanted. Your character looks as if he is floating as he seems to be sitting on nothing? (correct me if i am wrong here) but the butt should not be visible as he is on top of the pool side, which of course wouldn't be visible to the camera. same with the tail.
However, all in all, this is a pretty impressive piece! Keep up the good work! it's awesome to see you breaking your comfort zone. I hope my critique made sense and that i didn't ramble too much.