I drew mines on A4 but the actual size of the image is a lot smaller, maybe just bigger than A5. I found it a really hard drawing to do, I loved the photo so much and I don't feel like I've justified it as much as I wanted to. Like you I drew it rather quickly and it's one of those drawings that sometimes I love it but sometimes I hate it. I'd love to do it bigger so I can really concentrate on getting the skin exact as most of it just estimated.
I had a look at your one and gave you some comments, I hope they help
Great detail. I really like all the shade variations on his skin, with all the wrinkles clearly showing. Very good contrast too, especially against the black background and the white of his shirt. Nice work!