USB 3.0 compared to the previous older version of USB has undergone significant improvements. Probably the most significant difference is of course the transfer rate, which increased approximately ten times compared to the previous USB 2.0 interface. Theoretically USB bus brings transfer rates up to 5 Gbit/s, as it is seen from the characteristics of the physical layer interface.
Of course this transfer rate at the end of data transfer interfaces cannot be reached. After counting the losses caused by 8B/10B encoding (20%) and data encapsulation in a data link protocol layer (about 2.4%), we obtain the highest possible transfer rate circa 3.88 Gbit/s.
The specification USB 3.0 indicates really achieved transfer rates above 400 MB/s (i.e. 3.2 Gbit/s).
Nowadays, even transfer rate 3.2 Gbit/s is relatively high transfer rate that USB 3.0 can compete with most existing high-speed interfaces. One of many examples of practical use could be connecting devices using Flash memories such as memory cards, flash drives or hard drives currently popular SSD (Solid State Drives), which are capable of at least partially take advantage of the offered transfer rate.
Application of USB 3.0 will therefore especially when we transfer large amounts of data. More simultaneously performed OUT transactions together with one IN transaction then it also means the possibility of simultaneous utilization of the bus by multiple devices even send data to a host can actively only one of them. In the data rate can better compete with interfaces such as eSATA (external Serial Advanced Technology Attachment), which had so far in the transmission of data on top.
Currently, the only serious competitor to USB 3.0 interface appears Thunderbolt interface, which it is in essence an external PCI-E (Peripheral Component Interconnect - Express). It offers even faster than USB 3.0 and it allows in addition the possibility of chaining devices. Currently Thunderbolt interface is used practically exclusively for the products of the firm Apple.