The main technical novelty of USB 3.0 is that it raises to 4.8 Gbit / s (600 MB / s) transfer capacity at present is 480 Mbit / s. It will keep the copper wiring to ensure compatibility with USB 1.0 and 2.0 technologies.
USB 2.0 cable has four lines, one pair for data, a power and ground, in the USB 3.0 adds five lines. Two of them will be used for sending information and two for the reception, so that two-way traffic is allowed in both directions simultaneously. Increasing the number of lines can increase the transmission rate from the 480 Mbit / s to 4.8 Gbit / s. From this derives the name which also receives this specification: SuperSpeed USB.
The amount of current that carries a USB 1.x and 2.0 is insufficient in many instances to recharge some devices. USB 3.0, increases the intensity of the current of 100 milliamps to 900 milliamps, at which batteries can be charged at a higher speed to feed or other components which require more power.
This increased intensity might result in a lower efficiency. But thinking about it, USB 3.0 uses a new protocol based on interruptions, unlike the previous one which was based on querying the devices periodically.
Increasing USB 3.0 lines causes the cable to be slightly thicker, a major drawback. If until now the cables were flexible, with the new standard these have a similar thick cables used in Ethernet networks, making it more rigid.
Fortunately, as happens between USB 1.1 and USB 2.0 compatibility is guaranteed between USB 2.0 and USB 3.0, thanks to the use of similar connectors, whose additional contacts are in parallel, so that should not affect use any port that is not is the same type.