By comparison, USB 2.0 looked like a dog cart in the Kentucky Derby. Depending on the test, USB 3.0 proved to be up to 3.5 times as fast and always more than double USB 2.0's speed.
Of the three desktop-size models (each with a 3.5-inch hard drive inside), the Western Digital My Book 3.0 was fastest overall, with the Buffalo and Iomega drives finishing right behind it. The drives were separated by mere seconds on almost all of our read and write tests; we saw the greatest distinction on our malware scan test, with a span of 24 seconds between the fastest (Western Digital) and the slowest (Buffalo).
Portable drives always lag their desktop counterparts in performance, simply because of their slower rpm (rotations per minute) speeds. As such, it's no surprise that the portable Seagate BlackArmor PS 110 was not as fast as the desktop drives evaluated here. However, among the portable drives we've tested, this model leaped into second place; only the WiebeTech ToughTech XE Mini 500GB, tested over eSATA, bested Seagate's USB 3.0 portable.
In PCWorld Labs power consumption tests, we found that the average power draw at any given time for the USB 3.0 drives was slightly greater than that of USB 2.0 while data was transferring. However, since USB 3.0 does things far more quickly, multiplying the average draw over time shows it doing roughly twice the work per watt.
Beyond performance measurements, USB 3.0 has a huge edge in convenience over eSATA. Unlike eSATA, USB 3.0 was designed with removable storage in mind. It's hot-pluggable--you simply plug in a device, and your operating system quickly adds it to the list of available devices. By contrast, eSATA drives nearly always require a system reboot to appear.
Furthermore, since USB 3.0 is a powered port, you don't necessarily have to run another external power supply to the drive as you normally do with eSATA drives. Most 3.5-inch hard drives, however, require more power than the USB bus can deliver, and those models will still need AC adapters.
Certified USB 3.0
One of the things to look for when buying a USB 3.0 product is the certified SuperSpeed USB 3.0 logo--a label that will ensure that the product you're purchasing truly lives up to the new specification.
At this point, though, expect companies to release USB 3.0 products without official certification or the SuperSpeed logo. An example is the Buffalo Technology HD-HXU3, which was the first drive to market; and LaCie's drives, which are in the process of certification, will initially carry LaCie's own logo for USB 3.0 (the company says it plans to put a sticker on the products' box once certification is completed).