Hello Brunella,
Well, this is really quite striking! I have to say that on my monitor it appears very contrasty and the whites appear blown out - as they often do on photographs. I do very much like the artistry you have accomplished with deft strokes and artistic definition in the background.
I guess I would say that as a piece of art, it has a style about it that is artistic and striking, crisp and very detailed. If that is your goal, then you have accomplished it very well indeed.
If you wanted to achieve a portrait look that approached a more "life-like" appearance, then I would recommend focusing on creating proper variance in your edges as forms turn away, and creating more subtle value transitions. I am not all together certain what is happening with his eyes as one appears to be closed and one open? Again, this could be a trick of the photo of the piece, but the value of his left eye appears too dark and thereby makes it appear to sink farther into the head than perhaps it should. It draws my eye instantly. It may be less so on the original.
Again, it is a very nice piece and stylistically very well done!
I hope that helps.
Edit: Not enough coffee. In thinking about this again, what I really wanted to say is that if you desired a more life-like look to the piece, then you would focus on not overstating the values, varying values to achieve better effects of depth and turning of form, and give variance to certain edges to make the whole piece appear more dimension in the space. Again, I fully realize that this may be in part due to the photograph taken of the work, not in the actual work itself.