I've ranted about this before, so:
SM64 is still a great game on the DS, but the controls bother me too much to play it. You really need an analog, the d-pad just doesn’t work very well. You can use the touch screen, of course, but here’s the problem: The “neutral point” is always moving. If you touch the middle of the screen, then drag up, Mario will run forward…but if you drag up past the top of the “analog circle” on the screen, the circle will also drag up, moving the neutral point higher. So that means you have to constantly lift up your thumb and reset back to the middle! All the fun of controlling with a mouse, on a handheld! They should have “locked” the circle to the middle, or the side, or wherever, so the neutral point was always the same, like an actual analog stick.
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I really don't like the d-pad, you may not have as big a problem with it. The Lite probably has a better d-pad also.
Thumbstraps: I got my DS on ebay so it didn't have one. I went to my local Game Crazy, where I sort of know the people working there, and one of the guys gave me a strap off one of the used DSs in the case! I kinda feel bad for whoever bought that one, though.
I've only played MPH for a couple hours, but I really liked it. I thought the jumping worked really well (double-tap on the screen). It sounds like it would be annoying, but it wasn't hard to do. There's sort of low gravity in the game so you get this nice floaty jump that feels like the *suit* is jumping, rather than Samus, which I liked.