...IF YOU KNOW WHAT YOU ARE DOING with USB 3.0 and how to set up your computer ENTIRELY to take advantage of this feature. If you don't save your $20.00, because you won't see a difference.
I measured a improvement on a 10GB file transfer (with the factory Seagate USB 2.0 cord) at 24 minutes WRITE time (to the drive), dropping to just over 4 minutes with the new adapter. READ speeds (from the drive) took that 10GB file just hardly different than USB 3.0: 3 minutes vs. 4 minutes.
The nice thing about this setup is that in the future, this cable supports many other types of 2.5" drives that could read or write faster than what we have now. If future compatibility is your kick, then it is worth the $20.00.
Yes, eSATA is still faster than USB 3.0 on paper, but not for long. The internal components of computers are going to catch up fast to expand and meet USB 3.0's ability. My new 2011 Alienware has all-in-one-combined 3.0 / eSATA ports - I have not seen this on past laptops - so we may be on the cusp of the computer age taking another leap in data transfer speeds.
It really does matter if you know where your computer data stream bottlenecks at and how to use USB 3.0 properly; a lot of computers can actually NEVER move your data as fast as USB 3.0 (the computer is SLOWER THAN THE CABLE / KIT / ADAPTER), so why would you "buy a Ferrari to drive in rush-hour traffic"? (just for example)
5/5 Stars. For me, with the amount of data I move on a daily basis and with the high-end computers I use, USB 3.0 and the future opportunity is welcomed!