I was a little concerned by the fact that this is advertised as a Class 4 product, but, as others have noted, is actually marked as Class 2 on the MicroSD card itself.
I was, however, pleasantly surprised after performing a speed test on the device (via h2testw). The results were as follows:
This is in comparison to my previous Transcend Class 6 8GB card which records 6.93MB/s write and 13.9MB/s read (actually not bad for a Class 6).
All in all I am very pleased and also impressed by the performance of this supposedly Class 2 device (which in reality is almost Class 10!)