I like it, but I have to get a freaking Nintendo ID on there and waste 50 perfectly good cents on that crap.
But I've tried it on my sister's 3DS, and it is rather annoying. The way you have to transfer and switch boxes and games over and over is pretty dumb, since I'm pretty sure that they can make a transfer system that's not THAT complicated. Also I don't like the way the Celebi you get looks on there. I don't know why, but something about it seems off in my eyes.
...But other than that, I'm glad I finally got a shiny Sylveon, since I could never decide what to make it evolve into on my Black 2 game.