I really really like the details on his/her face.
You said you were unhappy with the torso part, and I am not an artist at all, so if you do not like what I suggest, remember it is from someone with no authority.
I do not really like the torso either, I think you need the same level of detail on the torso as the face. It is nice that since it is blank, the heart stands out more, but you could have the same stand-outyness by making the rest of him gray and maybe coloring the heart and eyes a really bright color. (All noir-ish, ya know?)
If it is supposed to be a robot, make him less curvy, add little buttons and joints and things and add bands around his wrists and define all the bendy parts with little mechanical thingies that would make him move. Like little knobs and pistons and screws. A belt at least. Robbie from Forbidden Planet without the michelin man look. If he is a person, just give him interesting clothes and some gloves.
Also I do not understand his right arm.
Add a background, he looks like he is falling off the top of a really tall building and waving. I think you should give him a parachute and draw that... Unless he is being super emo. Or whatever the background was supposed to be. Make sure he stands out from the background though, all dramatic-like. (Shade him really light and and background really dark or vice-versa.)
