Judging by when the legs bend and when they don't, I think you may have the frames of the side-view animation in reverse order. If you imagine him to be walking backward it suddenly looks more realistic.
Also in the side view, his arms seem to be on backward. This shows in the slight bend of the arm and the apparent thumb position. If you take the arm you have and mirror it, I think it will work well.
Also in the side view, his arms seem to be on backward. This shows in the slight bend of the arm and the apparent thumb position. If you take the arm you have and mirror it, I think it will work well.