What else is there to say? It works. It does its job (very well), there are thousands of codes for (probably) every single DS game imaginable. It's easy to use, and effective.
The reason I gave it a 4 in the fun rating is because it's NOT fun typing in codes that can have potentially 100 charcters into your DS, but luckily you can copy and paste it into the software that came with it, which saves a lot of tedious tapping with the stylus.
The only problem I had is when I plugged it into my PC, sometimes the software didn't recognise it, but this could be because I was using Vista, and it's designed for XP. So Vista users, beware. It works, but it takes some fiddling.