Hmmm, I dunno how to describe what's wrong with your art. Well, lemme try - it looks like bunches of separate pixels, your pieces don't look like a solid piece of art. Objects don't integrate. You know what, pixel art is a style of art, and if you want to do something as complex as you're trying to do, not just some tiles or small sprites, you must learn the basics of 'normal' art first, before choosing any style. And the colors, the lighting... light on the plague doctor is completely off.
VicariousE
Nah no bad comments here, though the only thing I spied, was the auditor's hand being a bit too large. Be sure to label your stuff pixel art!