Nice, a lot better than that Sibbering guy who portrays them as thick as a tree. The only thing I think is a bit off is the head size, which looks like it should be slightly bigger and not just the size of a human head.
Otherwise, this is definitely one of the best size comparisons I've seen.
Actually they don't have little heads. Read any of the Horus Heresy novels, and it describes how their heads are wider and larger than usual, giving them a brutish appearance than cannot be considered handsome.
It is so refreshing to see someone actual do the Space Marines in what are supposed to be their proper proportions. Giving them that imposing mass that makes them such super soldiers. Thank you so much for drawing this.