I had one, and it was so cheap I bought 2 (1 for my girlfriend). It worked great, was completely 100% reliable, and seemed compatible with every game I threw at it. Also, as new games came out, within a few weeks either DSTT or some good samaritan (Ashley?) would make a compatibility update. For $6 shipped, it seemed like the greatest purchase ever.
Then, the updates stopped, and pretty much no new games since January work on it. Good stuff like Bookworm, Sonic Racing, and now the new Pokemon games. So, I would not recommend it, no. Since for about $15 more you can get a card that plays all current games, and future ones.