@ar Pixels bigger than your eyes, and no touch screen. I've used a layout that fit a 16:9 display nicely before, basically top screen on the left, and then both screens stacked normally on the right. Worked well for playing Metroid Prime Hunters on a single screen device.
Screens this large won't make DS stuff that enjoyable honestly, and at that price point you could just get an N3DSXL, even a brand new one.