Okay, I just played through each of them for like a few minutes each, and to be honest, I'm less than thrilled, especially compared to the NES ambassador games. My main 2 gripes are:
1. No save/restore states. At all. I mean, if you exit out of the game, and you start the game up again, then you've basically just reset your game (as opposed to NES ambassadors and Wii VC, where your game is automatically saved and you will come back to where you left off when you start the game again).
Worse, the game will not pause automatically and go into sleep mode if you close your 3DS. There must be a huge technical reason why, because when you touch the bottom screen, it gives you a message in big print telling you as much. I guess you can always pause the game by pressing start and then close the system.
2. These games look bad. I guess the emulation is fine, I haven't played enough to make a good judgement. And the games look a bit blurry, though you can chalk that up to resolution issues. But every single game looks really dark-- like, as if you were playing on the original GBA. I have no idea why this is. I didn't have an SP, but I played (and still often play) GBA games on my DS Lite, and they look bright and awesome. And I'm sure that it's not a settings issue, because there are no settings you can mess with. I have my 3DS with the brightness all the way up. I also tried playing in native resolution, but no dice-- looks 50% smaller, but still no brighter.