Something to think about when you're doing the walk: his feet aren't visible inside of the film gate. It doesn't matter if they slide. However, if you are going to show the feet, then there are a few ways to keep the feet from sliding around. One thing I'm noticing is that it looks like your character is traveling a greater distance than his actual stride. How is your character rigged and what's your animation workflow? If I knew those things, I might be able to give you some advice on keep the feet planted.

Another thing to think about is the up and down motion of the body. Your character doesn't have any noticeable bounce to his walk. It doesn't have to be super cartoony and exaggerated; there just needs to be something there to give him a sense of weight and mass.

Overall, not bad. Keep up the good work.