Hey that's pretty cool!
Very impressive... you have a great style there.
I find one of the biggest challenges that I come upon is making everything in the scene "fit" with eachother. I seem to always have one object seeming realistic looking... another will look like a cartoon too much, and yet another will look good but just of a different style. I've been trying to work on keeping things of the same style, whether it's a watercolored look, a realistic scene, or if it's all sketchy looking... I find that the images are more impressive if everything looks like it belongs there, rather than if you try your best to make it photorealistic.
Anyways... what I'm getting at is that all the objects in your rendering have a great singular 'look' to them. Bright, vibrant, saturated, and a little whimsical touch as well... it's great!
How much time did it take you to complete that?