You've got the right idea, but the most obvious problem is the bad looping. Try and make the last frame as if it were the frame before the first frame, so the transition looks natural and the viewer doesn't even notice it.

Secondly, his hands bob back and forth as he swings his arms, instead of smoothly transitioning. Also, at no point does a person straighten their arms during a walk, you'll notice in the animation that the front arm pops forward to straight on the loop. Also, the head bobs are clunky and not at all smooth.

Thirdly, the waist point doesn't move at all. Even if he is walking on the spot, perhaps a smooth hardly noticeable forward and back movement on the step would lend a much more natural looking walk.

Still, don't be disheartened. Everything I mentioned is easily fixable, and when they are fixed it will look pretty nice. Just add a few more frames and make sure the loop reset is smooth and unnoticeable.