USB 3 is backwards compatable. So if you plug a USB 3.0 device into a MBP, it will just run really slowly (USB 2.0 speeds).
"10 times faster" on paper
USB 3.0 is capable of transfer speeds of up to 5Gbps (gigabits per second); that's a little over 10 times faster than USB 2.0's 480Mbps (1,000Mbps equals 1Gbps). In practice, it won't always be this much faster mileage may vary depending on hardware configuration but it will always be much faster than USB 2.0
How much faster ( xpressed as a percentage) is 3.0?
I know that Usb 2.0 is better than 3.0 and it is speedy.