We paid almost $100 per night. We were assigned to room number 405. It was the most awful room i have ever seen in my life. Very small, the bed was impossible for 2, with view to a wall, the a/c very close to the bed and very noisy. We inmediatly asked them to be changed. They changed us only the second night to room 308.This room was much bigger than the first and the bed was OK for 2 people. Still the a/c was very noisy and the TV was extremely small. The breakfast was ok but not a big thing.
They then explained to us that rooms ended in 5 or 6 were smaller than the others and only recommendable for people staying a few days. I do not believe those rooms are recommendable at all.
Location is good.

Atlantis Copacabana is a very nice hotel. My room was $80.00 per night and I was there for 9 days. What I loved most about the hotel, was the location. Beautiful block, easy walking distance to Ipanema and Copacabana. On a previous trip, I stayed at the Martinique Copa. Beautiful hotel, great breakfast, okay location.
What I did not like about the Atlantis Copacabana, is it could use a little repair. Furniture gets a little old and some things in the room need to be fixed. A little more attention to detail. . Their breakfast was just okay, and I thought the front desk people need to have a nicer attitude towards their guests.
That being said, Atlantis Copacabana offers a lovely stay in Rio de Janeiro.

Does exactly what it says on the tin. Nice spot and breakfast is class. Be careful in Rio. Had a gun pointed to my head but as advised carried out enough for the night and spent every penny of it. Leave everything in hotel safe (own safe in room). Not a bad area, this can happen anywhere. Spilled out my pockets and the two guys searched me themselves. The Islands trip for 100 reais is worth it. Dive point (diving 2 hours outside rio) is expensive but worth it. Class fish and saw turtle too.
Take Care.

I'd agree with most of the other comments here. This isn't the most luxurious place I've stayed in. It seems like some of the rooms are more dated than others. Ours was on the 8th floor and although clean and reasonably sized (although a little oddily laid out) had seen better days! The card for the lights was annoyingly erratic and several times we would suddenly find ourselves plunged into darkness. Breakfast was good and the staff were all helpful.

The rooftop terrace and pool is a nice place to start / end a night, has some great views of the city and seems a lot more modern than the rest of the place. There are a good number of places within a 10 - 15 minute walk to go to at night.

The location really is excellent, with Ipanema and Copacobana beaches only a few minutes walk away. Because of that it is a little quiter than some other locations which is nice and we felt quite safe walking around day or night.

Overall, a reasonable place to stay in a good location and fairly cheap.