I love the Handwriting Without Tears products (fortunately my district has plenty) and the concept of Mat Man particularly. I think there is a huge advantage to be gained in spatial awareness, prewriting, and body awareness from teaching Mat Man. There's even a cute online game that even includes the song (requires a free login). I've used the manipulatives and drawing sheets for individuals and groups of preschoolers this fall.
Here's some photo results from kids who used the manipulatives or interactive game first and drew pictures onto frames second. I love the repetition to cement the ideas, and the progressively more empty drawing frames to chain the task.
This drawing is by a child with autism in a 3 year old classroom with just a few prompts for parts. She drew fingers independently. She so often refuses to attempt anything on paper or try anything herself but she loved doing her drawing on her own. I enjoyed the pig nose and muppet eyes, personally.
This one is by a little 4 year old with autism in a special education classroom. He had a couple of cues as well and could write his name on the back too.
This one is by a 5 year old in general education preschool. I only interfered after he drew the first hand. Undoubtedly, this Mat Man will be an excellent piano player.
This one may be my favorite, just because I know the child. He is a 4 year old with autism and severe behavioral issues in a special education class. He loved building the Mat Man and worked really hard to make it match the picture perfectly. And he drew this with only cues for ears. Granted, he has fingers without hands, but I think this is pretty stunning given that he previously would not copy a circle. It was so great to see him calm, happy, and attentive throughout the activity, and he was proud of his work.
I was really pleased with the reception that the Mat Man activity had with the kids, and also with the results. Not everyone had such terrific results, but all these are after one session only, and I think there is great face validity to the concept.