I was very skeptical because of the low price, but wanted to be brave and have bought me. Initial tests in my laptop card reader is very positive (in Windows 8.1). I have the card once written completely full to test whether it has actually 64GB and cope with a continuous writing. That has made them easily. The write rate fluctuated between 40 and 55 MB / sec. The read rate fluctuated between 60 and 75 MB / sec.
The fluctuations may come from the type of files that I simply draufkopiert indiscriminately my photos and videos. So files between 1MB and 100MB.
In short: According to my first measurements a really great map at a great price.