more like Divine, than Marylin, actually

Well, the piece contains a lot of very unnecessary dithering, especially on the shark herself. I know that Blick's original piece has a lot of dithering also, but I personally consider it bad practice when it's not required. In this case it's being overused.

There is a problem with the line work in places too. Line work is particularly important in pixel art as those jagged squares, when done incorrectly, can look flawed ever so quickly. It's impossible for me to list off all of the weak areas. To help improve your line work, I'm certain there are tutorials over at Pixelation (wayofthepixel) that describe in detail how to do both line art and dithering correctly.

Lastly, and this one is less to do with technique and more to do with planning a good composition, the background seems very flat and detached from the shark. The shading on each bit of detail it seems random. Out of the two shading approaches, I prefer the dithering. In comparison the backjground feels lke an afterthought. The same applies to the floating fish. The random pixels, that presumably had been in effort to add more detail, make the background too cluttered. You should never shade this way and take more care when you do with regards to technique. Purely from a design point of view, as the background is the background, and it progresses towards and unseen distant horizon, there should be less detail than the shark.

I hope that wasn't brutal. This piece is certainly a cut above your other efforts.

What's wrong with the pixel work then? I do appreciate any comments and/or criticism. 

I think the concept is better than the pixel work in this piece. The concept is plenty of fun and it's testament to your creation that I immediately saw Marilyn Monroe in the picture before reading the title or details.

Although beautifull, i'm not sure i would be that happy to meet this sexy one around a corner!

Great and funny composition!