Any particular reason for leaving the top part black?

Higher contrast from screen to the plastic which presumably reduces eyestrain.

It maximises the 3D effect. Well, that's what they say. Not sure if they really had to make it black.

And (back to topic) that's the reason why I preordered a black one. It's got those layers which I don't like in the black one. But in the blue one you've got glossy blue, non glossy blue, light blue and black... it just looks like they threw a coin to decide which colours to put in   Looking at the pictures, that is. Does it really look so much better in real life? (I don't particularly like the black one, either, so...)

I wish the white one was real.

I'm 100% sure there will be a white one in the future.

I want the Red one you see on some pics :(

I personally have a hard time deciding which one is nicer between the black and the blue one.

I would love a white one. Sleek, classy, glossy and very modern looking. *Hearts*

Personally, I know I like the two-tone of the blue in this one. (Well, I know it's more than 2 total shades, but I'm looking at the open system.) It seems more colorful, and creates a nice contrast in things. I think I'd prefer a red one myself, but I don't see myself getting either black or white.

I'm the direct opposite of the OP. I find the black 3DS ugly and the blue one much more aesthetically pleasing. Doesn't hurt that blue happens to be my favorite color as well.

I really don't like either, the best combination for me would have been with colours outside while keeping the inside black. Even though the blue one is gorgeous, I'd have to go with the boring black.