He's so cute
It's hard to get over how adorable Batman looks in this. I am not sure why, but the style kind of reminds me of "Invader Zim". I think it's like that because the overall demeanor is fairly cute, but it has a sort of mischevious undertone to it. I think it's also largely because of the big bulging shiny eyes the character has. I doubt anything from the Joker is going to be good. I liked how one of his gloves seemed to be lacking hands altogether.
His head/neck seems to take up half his body! Of course, I have seen some pictures and cartoon characters that had it worse. While there wasn't much of a background, I think it was still nice to look at. It was mostly gray, but there seemed to be some shading in it. I also like how everyone was in lowercase to make it more innocent.