Thanks for all the comments so far! Some confirm what I already concluded myself, so below, a short lowdown...
It looks rather finished, but I can't help but feel it's still unfinished. Have you studied in anatmoy before? If not, I suggest finding some place online that can give you a quick rundown...
I hate to be the one to point it out, but his penis is rather low. Normally it stems from the center of the pubic hair...
Anatomy... the thing is, I'm not particularly good at that stuff. My method here was to first fire up Poser (that handy people-program) and I modelled a very simple male character somewhat like how I wanted the painting to be. Then I printed that out and did a sketch on my canvas. That proved a very hard thing for me, because I drew the figure on the canvas completely wrong.
Of course I fixed the sketch an awful lot, but some problems still remained. I just ordered a book on drawing human anatomy, so I hope that's a helpful thing to work with. I'll keep practising on it.
And the penis, yes... it's indeed too low. I thought about drawing even more pubic hair to sort of "catch up" with it, but I think that'll just look really stupid.
His hips seem wide and feminine. Also, the figure looks very flat. Perhaps you could add a light source, or change the shading to imply three-dimensional shapes.
Was the painter El Greco of mannerism fame?
The hips... good point there. Now that you've mentioned it, I can see that for myself. I didn't notice it before.
The painter, actually, is someone called Xavier Bartomeus who is likened to El Greco in several ways, apparently. Google came up almost blank on the man, though... so all I have to go by is a little bit of info in a book.
The painting he did was this one:
Don't know if I should've spoiled that one here... kinda takes away the originality from my own work.
About the shading, it's true... I first wanted to do a really dark-shaded thingy (like the painting from Bartomeus) but once the contrast of the dark background and the light skin came about, I liked that too.
I dig the style as is, I don't think deeper shadows are needed. The only problem is that the anatomy is too incorrect I think. The penis should be up higher, and the legs shorter (or knees higher whatever). Other than that I think it has a very nice rough quality to it which gives it a nice emotional quality. I also like the tiny tilt, really helps with the shift towards emotion instead of realism.
Do you mean the tilt in perception? E.g. that it appears you're looking at him from slightly above? That was what I intended, although I'm not very clear about what "tilt" you meant. If that is indeed the tilt you meant: cool.
I would think that the painting is ready as it is. To me it appears to be expressing tha growing misery of the world itself. This as a global wiev, but individually it brings up the wakening awareness to oidipalism and yet sexualism as not bipartite nor simple but rather most complicated...
It's hard to give arguments in a foreign language, but I hope I managed to say what I meant...
In all, I really like the way you use complementary colours to bring out the figure from the background, but yet not too much. I like it, in fact, if I had the money or the space, I'd buy it! 
Thanks for the kind comments! Although I'm not really sure what oidipalism nor bipartite mean, it's neat to hear someone has such thoughts about this.
Also, the space to spare shouldn't be too much of a problem... It's only 30 x 45 centimeters big... and as for the price? I have no idea how much shipping costs.
Once again, thank you all for the comments here. I've currently refrained from "touching up" on this painting.. I'm somewhat scared I'll mess it up completely. I'll have a go at another painting one of these days and see if I can paint decent eyes on that one...
If you have anything else to add about it, please do!
