I have an R4 that words on the DS, and it's amazing. That's all I know.

CycloDS is just like R4, except it can play all the games R4 refuses to play, it can do wifi cart-sharing with games like Mario Kart that cause problems on the R4, it has almost no glitches. Plus it has microSDHC support, allowing for higher capacity memory cards than R4. Plus, Team Cyclops is AMAZING at supporting this thing!
In fact, only the recent Square games' copy protection has caused problems, this is actually true for all cards though, and can be fixed by some simple Action Replay codes.
You should get it. You will not regret it.