I stayed here 3 nights on a business trip. The room is large with a seperate sitting room and bedroom but the furniture was old and worn. The bathroom was old and run down, but the shower was great and gave a lot of hot water.
The breakfast is mediocre, limited fruit and no vegetables. If you like porridge, fat food or sweet things you might like it.
I was charged an extra night as I arrived at 8 AM on the first day. I was not told this on check-in but informed on check-out that if you arrive before 2 PM they charge an extra day.
Staff smiles a lot but their English skills are very limited.
There is free internet but the bandwith was so limited that I opted to pay for a useable connection.
Pretty far from the city centre but not to far from Berrini subway station.

Close to work, great gym, great breakfast, big room.......only complaint was that the TV was at a weird angle in my room and was tough to see without some unatural body movemetns on my part....would go back!!

stayed for a night on may way in after a long flight. check in was quick and efficient. the room is well designed and comfortable. good selection on the room service menu. breakfast was good with a hot table and a good selection of brazilian and international dishes. concierge very helpful

I stayed in Estanplaza Nacoes Unidas for a week to attend a training course.
My first impression was terrible. The corridor to my room smelled. The TV wasn't working (30 channels in Potuguese but not a single one in English - the cable wasn't working and it took them 6 days to solve the issue). The carpet looked old and had huge stains. The couch in the small living room looked old and dirty as well. The old bathtub was full of black stains. I was turned off immediately.
On the positive side: very friendly reception staff (the only ones who speak English), a nice breakfast, free internet in your room and a very large bed.
This is not a hotel that I would recommend.