They say that the background is good. Probably because they don't want to tell You that Your characters are awful. You myst practice more. Try to work on piece until it's really good.

I too am loving this background.
You've inspired me to take on this medium.

I too think the character's don't match.
I think the background could have been dithered rather then a gradient.
But I like it still.

The part I like most, artistically, is the background. While I think you could've dithered instead of using all those colours, aspects other than pixel-technique stand out to me instead; The bg looks very foreboding and the tree and planet make it look psychedelically foreboding, which is very good. But I don't think the foreground really matches the style or quality of the background. The characters' colours kind of clash with the bg, I reckon. Not a bad piece overall though. I'm sorry to hear it came last, just keep practicing and maybe you'll come first one day :)