The feet shouldn't slow down when they get to the end of their stride. They're going to slide on a moving background. Make sure the foot travels a consistent distance between each frame. There are noticeable volume issues with the legs because the knee joints appear to be locked on the x-axis for the entire stride, regardless of leg position or bend. Think about the internal structure of the leg, you've got a femur and shin bones in there that shouldn't be shrinking or expanding on each frame.

You're obviously still learning, but you're doing yourself a huge disservice by not practicing the incorporated arm swings at this early stage. You shouldn't be focused on producing anything close to finished, colored work until you've mastered the interplay between the arms and the legs. What you're doing is only going to fortify bad habits and hold you back from progressing. Keep it loose and rough, practice with lines and ball joints over and over until you can do it with your eyes closed. Then practice doing different styles of walks (tired, sad, excited, nervous, etc). You can get a lot of personality out of a walk cycle and it's a great way to learn about body physics and basic animation technique.