Based on my experience, before you buy a 3G router, check its compatibility list first. Here it is: http://www.tp-link.com/en/support/3g-comp-list/?model=TL-MR3020&location=1151.
When you configure it, you need a computer to do the configuration stuff. Once it is configured successfully, you can access internet on other of your devices.
So you don't have to have a laptop/desktop everywhere you want to use TL-MR3020.