I Finally got the card in today and got it all set up. The card is pretty well made, heavier than you would think, and has a pretty nice UI. The microsd slot is spring loaded though and I am not sure whether I like that or not. If you plan on swapping games on and off it, or have several small microsd cards, I can see it wearing out or maybe even breaking completely and maybe rendering this card useless.
The microsd slot and the DSTwo going in itself were each a snug fit having to give a little extra pressure when putting in the memory card and inserting into the DS respectively making me question the fit and finish, but it works and will probably break in a bit after a while.
The DSTwo also has a function that increases it's CPU speed to help offset any lag or performance issues. From what I am told, it helps a bunch on the video/media player, but I haven't had a chance to try that out yet and not sure I ever will.
DS game compatibility is solid. From all the games that I tried, all of them worked including Chinatown Wars. Much better in this regard than my old CycloDS that just wouldn't run some of the games despite patching. From what I understand the onboard CPU helps with this.
GBA compatibility is great. I have gone through and tested a bunch and they all seem to be playing at (or very near where I can't tell) full speed. I did get a few audio glitches, but i think I will need to pull out the headphones to get a better listen. I love that I can play GBA on my XL now.
SNES compatibility is spotty. It booted and ran all the games that I tried including the Mode 7 ones. It does have some problems though.
The resolution of the DS is lower than the SNES so there's screen distortion when trying to squeeze the game onto the screen. It gives you 4 options with the squished default being the best one. The others chop off screen area considerably.
It has serious audio issues (not so horrible that you can't live with it), some worse than others.
It doesn't run full speed on many of the games that I have tried out, some better than others. Mode 7 games do run worse as expected but I was surprised to see them run at all.
The biggest problem here is that it's inconsistent and will drop a bunch of frames at once to try and keep up instead of just running at 80-90% steady speed and that makes the game unplayable. Even a game like Super Mario World was hard to play since you couldn't time your landings with the game stuttering in mid jump
Increasing the CPU speed from the stock "2" to "3" or "4" did little to help on most games. I understand the tech is there, but the emulator does need some work. Hopefully thy refine it.
Another small issue with the SNES emulator is that you have to reboot the DS to get it to change games. I say it's a small issue since the DSTwo OS boots rather quickly. There are ways to quit out from a DS game and the GBA emulator without rebooting though.
They have a port of MAME available based on an older romset and I thought I read about a Genesis emulator being made for this card, but I haven't been able to find anything about it so far.
Additional features of note that I didn't test out are the media player. ( .MP3 music and Divx .avi video are supported if that's your thing) and the ebook reader. I might give the ebook reader a go since my DSiXL has decent sized screens.
All in all, I am happy with the performance. I wasn't expecting much with the SNES capabilities and was more looking forward to being able to play GBA games on my XL and better DS game compatibility which this card does handily.