I really like the torso. The foreshortening on his right arm seems a touch off, as do the hands. Nice for a quick starting sketch, which you said this is, so...
*wants to see the 'longer version' (when you get time)*
That took you 30 minutes? >.<
It could use some work, but you're off to a good, slow start.
The anatomy and proportions are off, but that's alright. They're both a bit difficult to get down, especially when drawing men. You might want to study some Andrew Loomis a bit. He did some great anatomy studies, as well as figure drawing and creative illustration. You can view/download some of his books in PDF format here.