Dont understand

I downloaded this app before I read the other reviews. It is supposed to be a companion to Uber but I dont understand how it is different than just using the Uber app by itself. I only did it to get the $20 off my first ride but I never got it! So, I contacted Uber and sent them the screenshot of the apps promise and they refunded the $20 for me. Thanks Uber but what is this app and why would anyone need it??

Flick86 about GO: Discount for new UBER® riders