What should have been done differently on this photo?

A smidgen under exposed and the colors are a bit drab.

The shot was done at a wide angle (20mm) and this distorts the animals features but it does add a bit of quirkiness to the pic so it's not bad.

Really, just the under exposure and the drabness of the colors.

Perki's suggestion of fill flash is a good one EXCEPT that I'm a bit leery of using a flash on animals.

I like it! It's quirky and interesting. I think the composition is great. I, personally, wouldn't have moved the donkey over at all. The only thing that bothers me a bit is that it feels a bit dark. Can you adjust the lighting/contrast on your computer? The bottom seems very grey, and something needs to just pop out a bit. Otherwise, I really like it. Nice job. :)

You could white balance it so that his nose is not slightly blue, I would have used a fill flash to bring more life to his eyes and I would have used a longer lens with a shallower depth of field.

Edit: got to assure Eric that fill flash is used in animal photography very often.

it's a bit dark. Try adjusting the light and color. got photoshop? Maby try adding som hdr. (image-adjustmen-hdr) or a layer of hdr over this one on low opacity.

I would prob would done some more sky and bend my knees a little more but overall is good.

I think you need to adjust your curves a bit. It's a bit dark.

maybe it should be a little brighter

no but itd be cute if he had glasses and a hat on :))