I think they should've made it more AES-ish. That's just too square & boring for me. Also, fingerprints.
...what? This think is extremely SNK-correct, IMO. They nailed the aesthetic almost perfectly, even down to the fake CF originally used on the NGP. The logo is perfect, the joystick looks (I said, "looks") perfect. It's black.
Too square and boring? More like an AES? The AES is literally just a black square slab with a power switch on it. It could hardly be more boring. The most interesting thing about an AES is whatever cart is sticking out of it, and that's why it's so cool. There is no time for chrome badges and rainbow buttons when you are Pro Gear Spec!
The AES might not exactly immediately turn your head with some flamboyant design (and I tend to like those) and yes, it can be said that it's a bit of bore to look at. But you're a bit too harsh on it, I mean, it's not just a black box, it's black box with a
slope.

The magic is in that slope...and the bump around the cartridge port...and in the "lines" scattered symmetrically all over the unit. It looks like a competent piece of electronics.
I'll try and make my criticism against this new device more proper; To me, this looks like every other iPhone-look alike, complete with piano-black finish (which really is nothing short of retarted on a handheld - guess what it's going to look like). You may argue that the PSP sports the same look (and I don't really like it) and the same goes for the Vita (and again, I'm not really feeling it).
What I saw in my head when I read the headline was not this, but rather something like the NGPC or Gameboy or...the Sega Nomad perhaps. Not exactly pretty, but more interesting to look at. It's like the difference between some glossy piece of stereo compared to those big, black Hi-Fi sets from the 80s/90s. They have all kinds of displays, knobs, switches, inputs, outputs...and I love looking at them.
This, not so much.
But, at least it's got proper buttons. : )
/rant