My critique is that this piece has a lot of potential, but anatomy and shading are your biggest problems. The head proportion is deffinitly off, its way too big. Think about it, if the head was that big then the weight of it would throw the whole body to the floor!
The hand is also way too small. You need to remember that men usually, close to always have big hands, and most of the time are a lot bigger then a woman's. A good example is that your hand can cover your whole face, that's a good reminder the next time you have a go at them. (hands take a lot of practice but don't worry you get the hang of them eventually.)
The sweater is also off, not in color but in shading,which is a very big deal if you're using black. Without proper shading using gray tones the whole body now looks flat, which is a big no no since the human body is obviously not a piece of paper.
Shading skin is also very important. Without shading the skin you leave the face flat, but also paler then what it was designed to look to the audience. Examples of shading is the neck, clothing folds, hair)
Now, I am not saying this piece is bad. Everyone needs to start somewhere and I remember when my art was at this level. Just remember that this wasn't a failure, but it also wasn't a success... Not yet
+ That upper torso with the neck lines and the collar bones... it looks pretty good
- Your ENTIRE body looks 2 d. There is no depth to it all. Looks like he's made of paper... which he is but... the beauty of 2d illustration is the illusuion of 3d. Your piece has none of that
- Are the clothing wrinkles REALLY in the right place. Something feels off.
- That there nose isn't correct. I know your going for the small nose look but it looks like the nose is at an angle... for a head on angle that makes no sense. I'd suggest looking at Sorachi Hideaki (Gintama) or Komi Naoshi (Double Arts, Nisekoi) to see how to pull off the small nose thing.
+ The eyes are reasonably similar. That's difficult. You should feel good about that.
Ratings (out of 10. 10 means you are a master)
Execution Construction: 3/10. While there are no major errors in your construction, your body is tubular and what not. Really look how a real body works here. There are no OMGMAJOR flaws though. Line Art 1/10: Your line art is nothing special. They are sort of in the right places but it does not give this picture the sense of depth. I'd work in black and white and get good at that before adding colour. Colour: 2/10. It's not super bad... It's pretty meh though. Ruins the illustration. Really... I must stress if you aren't good at colour it works against you... always.
Vision Originality: 3/10. There is NOTHING original about this character design. Though... if that's not what you're going for... ok but... I've seen similar before... and it's not something that makes me say OH I WANT TO FIND OUT ABOUT HIM.. (But neither does Scott Pilgrim... or Moritaka Mashiro) Impact: 1/10. I don't feel moved at all by the genericness. This isn't a bad thing... Really I'd focus more on the technique bit. Then with all that good knowledge design good characters.
In the star ratings. Originality is a duplicate of vision... Impact a duplicate of Technique