SOO GOOD.
I got three beef tacos and it came with free rice & beans and they were the best tacos i've had in madison. This is the closest I've gotten to authentic street style tacos in the Midwest and am definitely coming back. They just started a new deal with Eat Street so I got 3 tacos for $4.99 which was awesome (you have to order it through the website though).
My friend got the plain tacos and they tasted phenomenal as well! They come with guac and with homemade chips, it's just so good.
They're a newish place so i'm sure they'll fix a few kinks (they did get reusable plates for eating in!) but definitely much better than what used to be there.