This bag is the perfect size. It fits my 3DS XL with tons of space to spare - I can fit the charger in beside it, a plastic case for 6 game cards in the netted top section (would fit plenty more cards lose, or more cases in the main compartment), and the front pocket is exactly the right size for an iPhone 4.
The zippers are sturdy, and there's an overlap on fabric around the top zipper,which nicely hides the zippers from view or sneaky fingers. The front flap also has a strong velcro fastening.
The bag itself is very well padded, you can tell that it will protect from bumps and even drops. The shoulder strap and fastenings are sturdy and secure, and handle is a nice wide one that fits very comfortably in your hand.
Overall, this was the perfect bag to buy to keep all my DS stuff together. I'm going overseas in a few weeks and this will serve perfectly as a bag for my DS but also for my phone and passport.