Overall, from a quick glance at it it looks very well done. =)
However, upon looking at it more closely, I see a lot that you could improve on. I notice you didn't get all of the tail cut correctly, as the other background it was on is still visible in places. To get the cutout to look better, you could've zoomed in to about 500-800% to pixel size, and smoothed out the edges on all sides of the image, letting the edges give more of a 3D look to it, rather than just appearing like a flat layer pasted on top.
Renders are a difficult thing to work with. A rule of thumb is, don't render the entire image, render the background or foreground, but not the entire
image, as it'll flatten it horrendously.
Colorwise- you need to heighten the contrast on the background and foreground, make them brighter. Right now between the image being flat, being dark as well, makes it even harder to find any depth, although there is a bit.
Another suggestion would be, try experimenting around with lighting effects, and emphasis on a certain color, and you might be surprised about how much your image will stand out more. =)
Sorry, I kind of went off on a critique rant.
I look forward to seeing any newer images, as you make them, to see how much you improve. =)