He has really long arms. I don't see why, but for some reason they look really long. :)
Let's start with the rig. He looks a bit weird with that big stomach. Weird because you can only tell by the sideview. From the front he looks normal. Plus he has skinny arms and legs. I would just get rid of the big belly. Right now it doesn't really add anything to the character.
Animation wise what stuck out immediately are his arms. They are very choppy in terms of movement because there are too many pauses and stops during the swings, they also need to swing back a bit more. The first pause is at x9 for a few frames, then at x21 and x28. Keep the swing uninterrupted. His left arm is also swinging too early. The end of the arm swing should be a few frames after right leg ends the forward step.
I would also add a tiny bit of side to side body movement (front view). He looks a bit locked off (especially that geometry piece above the hips).
The screen right hand's rotation is also a bit mechanical (front view) how it rotates at around x15.
Your screen right foot (front view again) is sliding towards the right after x12. It's also not moving backwards from x1 to x2 (side view). There can't be any pauses the moment the foot touches the ground.
You also have to have your feet roll off the ground. Look at x15 til x19. It looks like the foot just slides forwards. The foot needs to get off the ground and roll back a bit.
Good reference for that can be found @ Catty Wampus (love that name)
I would also rotate the feet out overall (front view). Even though they rotate out during the step, once they are on the ground they are straight forward again, default pose style.
Check out reference clips here and here.
The weight shifts in your hips are also happening a bit late, move it 2 or 3 frames earlier. The hips go up when the weight is on the leg. You have it go up after the passing pose. I also don't see too much Y rotation in the hips, don't forget to put that in there.
The head (front view) is also showing a few pops as it swings from side to side. Check your spine curves or your root (probably both). Make sure that you don't have unnecessary keys, double keys, etc.
Let's start with those fixes.