It'd be wonderful if you made more pony works (humanized or anything, doesn't matter). I really like this style of yours as applied to 'em. That loose flowing shirt and those shirts with the socks and sneakers, that colour scheme they got. That lovely pose, that amazing hair that's like mid-puff-explosion. The sheer cheerfulness of the pose and the impossibly cheerful expression. Love it so much. Also, the additional elements (balloons, cupcakes and stuff) are positioned well. The streamers in particular help the viewer's eye be guided to her figure naturally. Great job!