Not a bad walk. Assuming you're looking for a more casual, natural walk, here are two key things that I'm noticing.
1. He comes to almost a complete stop when his foot is under him, then the foot pops suddenly forward. When both feet are under this is the passing position. The rear foot is swinging forward, passing the stationary foot. This is the fastest moving point of the foot, when it swings forward. Having it slow to a stop at the bottom kills the momentum and then suddenly popping forward without easing, causes a little bit of a jerky movement. This might be good for a goosestep march or a peculiar walk.
2. The second thing is that the body's momentum should be relatively continuous. If you were to hide the feet, the head should be constantly moving forward, which would be the most efficient, energy-wise. Slowing between each step might be good for if he's pulling or pushing a heavy object, or if he's injured, where the walking would be heavily laboured.
Look into the four phases of a walk cycle: Contact, Down, Passing, and Up
in that order, they give you the four major key poses needed, and then you can add frames between them to adjust the pace
I highly recommend Richard Williams' Animator's Survival Kit, in particular for walks. Much of the book focuses on walks, and he goes into a lot of detail on them. There's also a video series, and I'm not sure how much of it, if any, is on youtube, but I believe the videos are basically a seminar he gave in which he goes over the exact same material in the book, so while it's nice to see it in motion, the book is really all you need.
