On the DSi ware front, i just downloaded Flight Control for 500 dsi points. Its addictive and has a local multiplayer. I would definitely recommend it. Its real easy to learn and hard to put down. You simply draw lines as the flightpath for planes to follow onto their respective runways. simple and fun.
There's a video on youtube of the DSi ware game in Japan that makes it look deeper than it is, I think the inside camera may be tracking it's surroundings and rotating the image based on how the real life background moves
I have the DSiXL and I will never ever go back to having a small screen. The bigger screen suits the camera function and allows you more space to mess around with pictures. Plus, after playing the DSiXL for a while, then trying to revert back to the normal DSi, you'll wonder how you culd ever have read the screen before.
It can be a tiny bit jumpy sometimes, but if you're not wearing skin colored clothes, it works fine. Same goes for the walls behind you, of course. It does do a better job of tracking things than warioware snapped