It's unfair to compare it to Antichrist. There are similarities, yes - a psychiatrist and his girlfriend go to a cabin in the woods - but the development couldn't be more different.
Personally, I did enjoy the movie. I liked the twist at the end and I hadn't seen it coming at all. The acting is really good and feels incredibly natural, like they are not acting at all. In fact, combined with the directing and peculiar camera work, it felt strangely immersing - like a reality show that is actually showing the truth. Since it's so strangely natural, someone who isn't sucked in might think the movie goes a bit slow. Personally though, I thought it was brilliant. I was very pleased and very impressed with Brazil's ability to produce good thrillers!
It was supposed to be a brazilian version of "Antichrist". Sadly it's too "brazilian" and less "Antichrist". Who was born to be Thomas Portella will never be Lars Von Trier.