The device works as expected, but it has some annoyances which I had not appreciated before I purchased. The good thing is that a hard drive which previously transferred data at 25MB per second under USB, increased its data transfer to about 98MB per second under eSATA.
The annoyances then... This device does NOT give you an eSATA interface in the regular sense. It just allows you to connect an external drive to the motherboard using an eSATA cable. That drive is seen by the computer as if it was an internal hard drive. Therefore, drives attached in this way are NOT hot-pluggable. I had to go into the BIOS to activate SATA sockets 3 & 4. Without doing that, the drives were not seen by the computer at all. With the BIOS updated, all worked fine. However, if I then boot the computer without that eSATA hard drive attached, the computer gives an error stating that it cannot detect the hard drive which should be in SATA socket No 3 (or 4). You can choose to continue the boot, ignoring the error, but it certainly is an annoyance. I for one will be deactivating the interface (in the BIOS) for regular computer use, and only re-activating it when I have a major backup job.
There are proper PCI eSATA cards which work exactly as eSATA is supposed to do, but those cost a lot more. This is a cheap and cheerful imitation. You gets what you pay for!!