Lots of blue... but still easily tellable what it is.

That's an impressive amount of detail for such a small canvas.

Wow, Thanks ! I must try, thanks for very useful opinion ! This was just what I needed ! :)

Nice theme and mood!

I think you can reduce the color count even further. I've had a quick shot at it (12 colors): see http://i.imgur.com/iDziC13.gif - I merged similar and/or rarely-used colors together. With a histogram tool, such as the one in Grafx2, you can identify "lone" colors that are used in 10 pixels or less; these seldom-used colors are easy to remove or merge. Of course, this leads to some details being lost. With some more careful tuning, I'm sure you could get this piece down to 8 colors :)