Well.....
The piece obviously leans into the neo-classical area, with its diagonal pose, and semi nude attire. The monochromatic depiction is clearly a nod to the polished marble statuary of the older era, suggesting purity and perfection. The physical body itself, obviously, is far from the ideal vitruvian proportions, suggesting perhaps a great irony or contrast with previous held perceptions of physical perfection.
The hands folded into his back would normally suggest a military bearing, but combined with the slanted stance instead suggests a certain level of shyness, perhaps at being mostly unclothed. This in turn would also imply that the subject is not a professional model or anyone who is comfortable at showing off one's body, but rather a more average citizen who likes to be put on display as much as the common man, which is not very much. This lends him a certain aura of sympathy, drawing the audience perhaps to look away from him rather than toward.
The expression itself is not fierce, nor ironic, humoured, or sad. It merely....is. Approaching Zen-like qualities of a Budda, the subject accepts his state of being and his place in the world.
So
obviously, blah blah blah