"Signal" Internet is wireless internet offering up to gigabit transfer rates. This seems too good to be true. What am I missing?

A new ISP in Milwaukee opened up and I recently became aware of it. They are called "Signal Internet". They offer wireless internet with quite fast speeds.

Wireless transfer technologies always seem flaky at best and rarely with gigabit transfer rates. Yet, that is what they are selling on [their website](http://www.signalisp.com/urban-internet/).

This seems like a good idea, but I feel like I'm missing some obvious problem. Can anyone here offer some insight?