Firstly, I suppose this does the job it's supposed to. It holds your memory cards, and that's what you bought it for.
However, considering it's just a piece of plastic about the size of a credit card, I was expecting a little more for the price.
The micro SD card slots don't retain the cards other than friction - no click to secure or release as you'd get in a proper device.
Secondly, the space to write information about a card is only around 1cm square, and could have been a lot bigger considering the rest of the space is taken up with the product name that's already on the other side.
Finally, it would have been a lot better if it wasn't made in almost exactly the same colour as the memory cards you'd be storing in it. They just don't visibly stand out when pushed all the way in. Simply making the plastic light grey would have been an improvement, so at a glance you could have seen which cards are present.
Maybe this is better than a case that cards could fall out of when opened, but I'm not sure I'd trust putting this in a camera bag either, as it's still possible to snag the cards and remove them accidentally.
EDIT: After my review, I received an email from the manufacturers. They claim there is a spring holding the cards in place (although it doesn't work like a proper device, there is a detent holding it in place more than just friction). Apparently they perform tests to ensure the cards can't fall out as well, such as spinning from a lanyard. They also say they are going to increase the size of the area to write on.
For this information I've upped the rating to four stars, as it's probably a lot better than it appears, but it would still be nice if the plastic was in a different colour so the cards stood out...