Deducted a star because I unfortunately had to cumbersome pull the correct driver from the network to me. Then: Impeccable! I ExpressCard - do not need shaft on Macbook, the card reader is easy there. It closes flush, even if an SD card is inserted inside. Therefore, no compromise on style and no protruding parts that can break. After rebooting and previous driver installation properly recognized and (subjectively) very quickly.
Addendum: the card is working perfectly after updating to Mac OSX 10.8, it needed no new driver