i think the background is a great concept and the kitty looks so comfy :)
but i also think your colouring is too inconsistent and could use alot of work where you have all of those white spots, you should use the solid tool (pen, pencil) for the initial colouring and then after that you should use the water colour or airbrush tool for shading and highlighting

You're not a bad artist. Maybe you just tend to leave some stuff done, moving on with a hurry? The lineart could be smoother and the colouring has some white blotches there and there. His lower half of body also seems small... I can see it's an attempt to create perspective but still.

Still, I like this one. ^^