Additionally, it's almost as fat as an original gameboy cartridge
One interesting thing about it, though, is that its GBA mode has built-in emulators for NES, GameBoy and TG16 (PocketNES, Goomba/Color and whatever the GBA-PCE emu was)
When you say almost as fat as a GBA card, do you mean it'll fit into a GBA and is not just for DS lite?
Also are the emulators hardware emulators or included software?
It's fatter than a GBA card - it's nearly the size of one for an original gameboy. It works in GBAs as well, not to mention both a NDS and GBA mode on a DS (though DS mode hasn't been updated in years so don't expect anything new to work.) It runs stuff off a normal SD card. 2GB is the limit however as it cannot read SDHC except for non-game media. It WLL read adapted mini/microSDs though.
The emulators are quite literally built into the hardware. If you put a GameBoy, NES or TG16 ROM anywhere on of the SD card and load it up in GBA mode, it will start running it in the respective emulator embedded into the card (I haven't used it in a long time, but I remember it ran PocketNES 9.97)
You can read more about them here:
http://www.m3adapter...OT-2_Series.htm
but my exact card is not pictured. The closest one size-wise is the M3 CF, but mine takes SD cards and reads from the front. I actually got it by accident from an ebay seller's "scam" offering "20 real games!" with a DS. However, instead of getting a dirt-common card like R4 ice cream christmas clone 9001, I got this XD
EDIT: Here's a picture comparing the thing to my copy of super mario land 2.
And yes, I know SML2 is yellowed to hell, it's the only GB game I have in that condition, but hey, it still works!