If everyone is still interested in doing a Commercial Critique, I'd suggest doing one for Legend of Zelda: The Minish Cap.  I think this is an incredibly impressive work, since the game art was done entirely by Haruki Suetsugu.  That's hardcore.

Hey Hannes!  Nice to see you still around and making excellent art!  CGA has to be the most evil palette around, but you've done some good work with it.  Overall, these are some very impressive portraits, but I have a couple of minor crits...

On the first one, I think you could articulate the detail in the hand a little more...kind of vague at the moment, and it's looking almost like he has three fingers.  In the second, I'm not quite sure if the light areas in the middle are his eyes, or under-eyes or glasses.  The only thing I can see in the last image, is that there is a slight dent in the brim of the man's tophat, right at the front.  Other than those very minor things, this is great work! 

Pretty interesting style, and you're off to a pretty nice start...  A few things I'd work on beofre polishing it up, though.  Firstly, the rear foot is turned 180 degrees from the front foot...certianly a possible stance, but not one that's very comfortable!  I'd have that foot facing the viewer, more at a 90 degree angle.  Second, with that much of the right side of his chest showing (our left), you should be able to see at least some of his shoulder.  The shoulder that is shouwing is also a little high, and looks more like an extension of his trapezius.

Finally, the lighting is a little off.  If your source is coming from the upper left, and the highlight on his forehead is as strong as it is, there should perhaps be a little more instensity to the shadows.  There's not much under his nose, and even without an ear, the side of his head is a little devoid of detail.  I'm totally digging your colour choices, though, and the style is very interesting.  I'm looking forward to seeing what you can do with this, if you decide to work on it further!