Not bad for a first, for my first few I didn't use shapes for the lines, but they make it look a million times better when you do.
It's quite easy to do the lines as shapes, it just takes a long time. If you haven't already check
http://www.slhess.com/wiki/index.php?title=Inkscape_tracing_tutorialI'm not sure how it applies if you're using PS or Illustrator but it's helpful anyway.
Lines are too thick anyway, and if you do use the line tools its pretty awful to have the square end. As it is the image looks like a parody image, so if that was the intention, well done, otherwise needs more work.
Also, the corner of the wall behind tenko's ear, the line doesn't cover the transition of dark brown to beige(?)