While you may not be awe-stricken by the size of the DS lite at first, you come to appreciate it quickly. It's noticeably lighter, definitely thinner, and each half is not much taller than the size of the screen it needs to hold, which makes the folded product much more pocket-friendly. It's not so small that your hands get cramped or anything, though.
The screens are brilliant. You can't ever imagine going back to the old system once you've tried it (kinda like how you couldn't possibly go back the the GBA after the GBA SP...or even the old GBA SP after the DS...or even the DS after the GBm or new GBA SP). The new placement of the mic feels more comfortable (in Feel the Magic: XY/XX I'd always bend down towards the corner of the mic to blow, but now with The Rub Rabbits! on the DS lite, I don't feel inclined to move a muscle).
The buttons are different. Not better or worse, just different. The + Control Pad and A, B, X and Y buttons are springy, but not so springy as the original GBA's or the GBm's: they're much firmer feeling. The Start and Select buttons are clicky, and their new placement takes some time to get used to, but just as always, you do eventually. The L and R buttons are probably the best I've felt on a handheld since the GBm: shaped like the GBA SP's, but built so close to the machine they feel like they could never come even the slightest bit loose.
I'm sure you've all seen enough comparison shots of the old DS and the DS lite, but I'll show you some of my own, anyways. Here are the styli, the screen brightness (old DS vs. DS lite and DS lite vs. GBm) and the sizes.
[attachment deleted by admin]