...whenever that comes out! (november, apparently)
A big plus would be trying to add more games to it. Either via an SD-card or with a cartridge slot.
But please, if you happen to do something with it, do a very detailed analysis of its internals! (my guess is that it'll be quite plain... but hopefully it won't be a glob top)
Altenatively to the usual stand up arcade cabinet design, how about a coffee/cocktail table, with a big LCD screen? And a removable joystick?
Could even be a round table to allow for co-op play, and as the console is so small, you might be able to have a lot of room underneath so the player's legs would have some space.