This is a feature I always wanted to have when I was an iPhone user, having support for USB 3.0 in the new port on the iPhone 5 was one of my bigger wishes, but Apple didn't add that to the Lightning port… Now Samsung has done that on the Galaxy Note 3. It's perfect for users like me that transfer large video files to my Mac, that I have recorded with the phones camera. I use Final Cut Pro X as my video editing software, and waiting for these files to transfer to the Mac from the phone feels like precious time that I lose everyday.
It’s not a feature that’s been talked about much, but it offers multiple benefits. First, speed of file transfers with a USB 3.0-enabled PC will be faster, a welcome change from the slow speeds we’re used to on smartphones right now. The other benefit will be when charging – USB 3.0 provides up to 900mA output current, higher than the 500mA of USB 2.0, so you won’t have to worry about extremely slow charging
Source: Samsung Galaxy Note 3 sports USB 3.0 connector for faster transfers and charging | SamMobile