PS7 with a reference photo, not sure about how long it took, but I didn't bother too much with the details:
"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram
Reference or painting over? Either way, pretty good. Somethings to work on would be keeping your lines... Straight, too squiggly tend to seem very rough, but the way it's presented here isn't too bad. Keep improving.
"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram
Also a suggestion, but this is just my thoughts. The messy dry brushes down the trees really distracted me, you should try using bigger brushes when doing things like those trees
PS: I'm getting better at this constructive criticism thing aren't I!
Strange, I didn't use any dry brushes at all, only soft PS airbrushes. Of course, the original image size was 3800x4500, so using a relatively small (50 px or so) brush would likely make smooth edges quite sharp on a small resolution like this.
And yes, it was good criticism. Oh, and a reference photo was used, no painting over. That's stupid.
"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram
You may want to refrain from using big image sizes until you can do the detail to actually make it worthwhile. Otherwise it will detract from smaller details.
What I've learned from living in this country : America is a bad word, so is Religion.