Update:
After about 11 months of use, the reader pretty much cracked and stopped working. Given that it's such a small device, and on my key chain all the time, this still seems like a reasonable lifespan. It still protected the memory card, so I was able to reuse it when I got a new reader. I regardless, I'm going to continue to recommend this just because of how small it is, but I suppose you just have to be aware that it's more fragile than I initially thought.
I've had this since January, which means that I've been using it for around 6 months. It has worked flawlessly. I keep it on a keychain with other keys and it is always in my pocket, which means that it is subject to some pretty harsh conditions. However, it has held up very well. The black paint (which says kingston) has all worn off, but it has exposed a nice silver-metal color. The body appears to be mostly made out of metal.
Reliability is really based upon which microsd card you choose to use with it. Currently, I have an 8gb card. But if you have an unreliable card in the device, then the device will obviously appear to be malfunctioning even if it is not.
My only advice, and this is based upon personal experience with other products, is to apply a few drops of liquid super glue to the knot at the end of the lanyard. This will prevent it from coming undone and possibly allowing your reader to come free from your keychain.