I'm Brazilian and I can say: that's the least authentic Brazilian restaurant I've ever seen (and far far the most expensive). We paid for "as much as you can eat" but they stopped serving after 2 hours. They came with meat to my table only 2-3 times!! That's seriously ridiculous if you know how a Brazilian restaurant is! The meat was low quality, the food is not good either and the waiters were very unsympathetic.
The show is not authentic at all and the dancers are not good. It passes a completely wrong idea about the country.
If you want to eat good Brazilian food, just stay out of it. Go to the center and you'll find other places there, even Brazilian ones. Way cheaper and way better than this one.
Additionally, don't buy the Groupon voucher! It's a trap. You'll spend the price of the voucher plus 20 euros per person that you pay there for drinks. They told us it's mandatory while on the voucher says it's optional. Anyway, the prices of the drinks are very high. So you'll spend a lot for a low quality food and service.