As a sketch from a drink-n-draw session, this is really solid. Even though it was done on the fly, you have lots of great details and a good composition.
What I like about the composition is the balance of black placement. The dark tones on the legs and hands give it good balance. I think the only addition that would improve this would be a few dark shadows somewhere around the head. While the hands seem to be the focus of the image, a little more attention to the head would not detract from that. Since his costume doesn't have any dark tones around his head, your options would then be limited. But perhaps a cast shadow, or a L.o.S.H. logo behind him would help.
The figure itself has some good qualities. Particularly the twist. Figures always look more interesting and dynamic when the hips, torso, and head point in different directions. It's a classic superhero pin-up pose. My only concern is that his left leg might be a little too hidden. I understand that it's the issue of the angle of the viewpoint and the twist of the pose that hides his lower leg, but I think you could have indicated a little of it behind the right knee. I don't think it'd be ambiguous, because the black shadow of his leg would contrast against his white boot, and if you did the cast shadow, that'd help too.
Again, this is a fantastic sketch. I love the clothing wrinkles, the highlights, and the energy you have in the lines. The fact that his belt pouches loosely flail around his waist is a great detail. I wish you could have had the opportunity to vary the lineweight on him, but since it's a sketch, there's no reason to expect that (but for future experimentation, you might try creating lineweights with the ball-point pens you use).