The walk is funny!
I would smooth out his left hand rotation or just slow it down a bit during the loop. There's a quick rotation, which could be okay, but it stops also very abruptly and doesn't ease into that stop that much. Playing it at full speed it looks a bit poppy.
In the front view, I would tweak the arc of the screen left arm. As he swings it forward it has a C curve, but on the way back it follows that same arc. So it feels like it's a poseA to poseB back to poseA thing. I would it have an underarc as it swings back, so do a C curve and then a flat underarc back, so it's more like a squished O (like the other arm, idea wise, but not too similar of course). You should try to have a poseA to poseB, back to poseC type of structure with different paths between each pose, using arced curves. Whew, that was a mouthful.
In the front view again, watch his head as it swings from right to left. It's a pretty quick move and again with a quick stop. Slow down that stop.
Sideview: watch his right foot on x14. It stops until around x17. If you have that guy walk from A to B, the foot would be sliding at this point.
Same thing happens to the other foot from x0 to 4.
Watch as the feet lift off, like the right one on x6, then stays in the same position on x7 and then keeps on moving. Watch the spacing during that section.
Given the swingy nature of the guy and rhythmic walk, you could push the hips a bit more going up and down, to really sell the weight shift and how each leg pushes one side of the hip up during each step.
Sideview: I would move/translate the head more forward and backwards. Not rotating up/down, but adding head pose where the head sticks out to the front more (while keeping the nose straight and not down/up). Same thing going backwards. It doesn't have to be big, but enough to break up the shape between the head and the upper body. Right now they both feel like one unit.
Reminds me of Gene Wilder in Transamerican Express. :)
Hope that helps!