BigNumber
Plugged in and worked out of the box in my Samsung Note 2 (Verizon).  Using an app to test the speed while it's in my Note, was hitting 8 - 15 mb/s for writing (avg high 8s), consistently in the 10mb/s for reading, so this seems like a legit class 10, and I don't think the write test really worked the greatest for whatever reason.  I'm with WinXP still, but to anyone else wondering, the exfat format the card comes in is what you want, don't format to fat32 if you computer can't read it, your phone/tablet/etc. most likely will read it fine.