This card has a bit of a mixed review. So I decided to do a benchmark test. And here are the results:
Largest test file 500MB
Sequential Read : 9.569 MB/s
Sequential Write : 4.102 MB/s
Random Read 512KB : 9.563 MB/s
Random Write 512KB : 0.647 MB/s
Random Read 4KB (QD=1) : 1.180 MB/s [ 288.1 IOPS]
Random Write 4KB (QD=1) : 0.006 MB/s [ 1.4 IOPS]
Random Read 4KB (QD=32) : 1.184 MB/s [ 289.1 IOPS]
Random Write 4KB (QD=32) : 0.007 MB/s [ 1.8 IOPS]
Yes, this card is in fact technically class 4. If you are transfering files from 0.5MB+ then you should get best performances. The downside is when you start transfering smaller files, read and write speeds go down(this is to be expected with all media storage) but this card under performes in this area, my class 2 cards perform slightly faster here.
In conclusion, if you're gonna use it for music and small videos then yes, this is a very good card.
If you plan on transfering 1000's of tiny files e.g. cache files, small text documents etc then be prepared for slight performance issues.