First of all, I really like this work, the composition is pretty classical, and works very well. The idea of combining a quote and portrait is classical too. The choice of writing style is pretty and fits well here, though some words are hard to read. Some letters conjunctions look like you've based the writing on some PC "handwriting" font e.g.: the word "myself" - "lf" conjunction, "comfortable" - "or", "om", "own" - "ow". I hope you understand what I mean, letters have conjunction lines, but are not joined. This effect is typical for machine font, not for human handwriting.
Drawing. I know you don't have much time for practice, and considering this, your skills are pretty good. I really like how you've drawn his eye, vivid, natural, nice details and neat shading. Proportions are pretty good, though you had to draw his hair using your imagination and I'm not sure if you haven't done too much of it. I would draw his hair flatter.
Another little hint for hair - try make a "shape forming" shading first - show the main shape of his hairstyle, define really large strands, and only then work on details - some hairs. It can give a more "whole" look to hair, though I don't know if this method will work for you.
I'd like to notice the work you made on his facial hair, very neat, very detailed, I can imagine your efforts (and you know I don't have enough patience to do the same). A little note for the next time - try to vary your hand pressure, to get a better blending.
As for reference - following Jeremy's quote, you've definitely chosen not the most comfortable one, with overexposed shadows. And it's pretty hard to draw from such references because you don't see all details effortlessly.
So, to sum it up - Impact - excellent, because you did a really great job, and you found time to finally draw something. Vision/originality - classical. Technique - you still have things to learn and work on (and me too, wouldn't be fun if it was otherwise), but you're making a good progress.
My gosh, so handsome! That eye is so lifelike; it's like it's staring out of the screen at me! Kudos to you on having the patience for doing every single strand of that facial hair (and hair and eyebrow). The shadows look really good, too! I love that man... You're not helping, either!
I like a lot how you drew his eye, very vivid and natural. And I seriously think you should draw more, because it'd be unfair if you won't, you're really progressing even though don't have much practice ^^
I can imagine! Always happens to my drawings. I'll write you a better, more detailed critique later if you want. With some hints. But for portraits - if you want a critique it's better to give a link to the reference.