For those with thunderbolt port, this is faster than USB 2.0. Though more expensive, you gain the faster speed as compared to USB 2.0.
However, for those with USB 3.0 port, you can stick with USB 3.0 as Thunderbolt does not offer much speed gain over USB 3.0 and USB 3.0 is much cheaper.
Check the following comparison out:
Seagate GoFlex Turbo Review. Thunderbolt, USB 3.0/2.0, Firewire 800 - YouTube
However, for those with USB 3.0 port, you can stick with USB 3.0 as Thunderbolt does not offer much speed gain over USB 3.0 and USB 3.0 is much cheaper.
Check the following comparison out:
Seagate GoFlex Turbo Review. Thunderbolt, USB 3.0/2.0, Firewire 800 - YouTube