The included accessories are all straightforward and don't really "perform," at least not in the literal sense. For me, the biggest draw are the extra styluses. If years of DS ownership taught me anything, you can never have enough styluses. Even if you're incredibly careful, it's hard to not lose at least one, so you'll always need spares. The stylus that comes with the kit is identical to the one that ships with the system. There's no chance of the tip scratching up your screen and it fits snuggly into the system's stylus holder.
The plastic cases are another major plus. There's a tri-fold case with room for up to four 3DS or normal DS games as well as two single-cart cases. I preferred the tri-fold case to the singles. It holds more games and isn't as easy to misplace as the smaller, single cart ones. Games don't slip around the case and its small enough to place in your pocket or bag.
I have mixed opinions on the screen protectors. I love the idea, and while I have one on my iPhone, I've never had the need for one on my DS thanks to the clamshell design. Both protectors slip right on to the screens without any problems or hits to performance. The bottom screen is just as responsive and the top screen doesn't interfere with the 3D effect. I ended up removing the top screen protector though. Unlike the bottom one, it's noticeable and a bit distracting.
