Underswap!Sans

The pose looks a bit too weird. Mainly how the legs are. They look like he's slowly falling backwards and is in that split second in which he hasn't realised it yet.

In my opinion, the hands/gloves have wrinkles in all the wrong places. I mean, if he had proper wrists instead of skeleton wrists (Fleshy ones, I mean) and the gloves were tight, i guess it would have those little wrinkles and such.

The bandanna looks weirdly shiny in my opinion, but hey, I'm just one person saying what they think about it.

Anyways, the pros are the fact that this looks pretty damn nice in terms of colours.

In short:

1. Pose looks like he's going to fall on his butt.
2. Gloves look weird.
3. The colour is nice despite those two facts.

I recommend you redraw it at some point, it looks okay!