The pose is quite stiff and unnatural mostly due to that right arm/hand and his left leg; but I think rather than telling you what the issues with this particular pose are and how to fix it, there are a couple of things you should do that would be the most effective in helping you improve.
The first is to learn the fundamentals and go back to basics. I'm not sure but it seems that you didn't construct this figure using broad gestures to start with to get the pose but I think you drew each "piece" one after the other?
The "proper" way to go about drawing the figure well is to first do a simple and quick gesture drawing that nails the proportions, balance and pose of the body within the first couple of minutes. These are gesture drawings:
https://www.google.co.nz/search?q=gestur...24&bih=609
You can use sites like
http://artists.pixelovely.com/practice-t...e-drawing/ which automatically switch models every so many minutes to practice. Or you can do it in a sketchbook with real people out and about. You don't need a lot of time to practice gestures, a couple of minutes for each one can be enough. This is something you need to constantly practice and then apply to every piece.
You then need to start learning about constructing the figure in terms of volume and not outlines. Buy / borrow / steal all the Loomis books you can and read them all. They used to be available at saveloomis.org for free but they are back in print now so the free versions have been taken down. "Figure drawing for all it's worth" is the one for figure, but you should get them all. They really cover the fundamentals well.
Bridgman is still available for free online.
http://www.drawingbooks.org/bridgman1/index.html
Once you've got a few (hundred) of those studies under your belt and you've had a look at Loomis' and Bridgman's construction techniques, then come again at this piece and construct the figure properly from the ground up and see how much better it will be. I know that's perhaps not what you wanted to hear, but it really is the best way to get better at this. Hope that helps
Oh also you never mentioned what this illustration was aimed at..card art, concept art, just doodling etc. This can be useful for anyone who want to help you with a crit. :D