I was looking at your pattern and I don't see anything that would make it terribly difficult. The picot hem might be a reason for classifying it intermediate, or maybe working the heel flap and doing Kitchener stitching on the toe. After you work the leg you should be able to determine a stitch count to fit your foot and if you need to decrease, just divide the decreases evenly or do a triangular shaped decrease on each side of the sock.
~ GG ~
This is the last time I'm frogging this project for the last time.