I purchased this tiny micro-SD card reader on ebay not too long ago. I was fascinated by the idea that the SD card was small enough to fit into the space under the USB plug's contacts, normally occupied by PCB, plastic, or some other backing material.
In testing, using an 8Gb Transcend micro-SD card, I was interested to see that it could easily reach full USB 2.0 speeds (on writing as well as reading). It seems to be reliable enough, however I have noticed that on occasion the sd card will become partially removed when pulling the adaptor out of the usb port, however since it is already safely unmounted when being removed, I don't think it is too much of an issue (provided one checks to make sure the sd card is not missing from the adaptor before putting the cap back on). I've not experience any data loss so far.
I've cut off the larger loop of nylon on the end of the adaptor, and tied the loose ends of the smaller nylon chord into a reef-knot, before securing it with some super glue, so It fits on my chain of assorted usb devices a bit better. I intend to keep using it as a USB flash drive, and swap out the sd cards as I need more capacity from now on.