My stay at the Arena Ipanema Hotel was okay, but it didn't feel like a 4-star experience.
The staff was nice and helpful, which was a plus. However, the room left much to be desired. There was a bad sewage smell from the bathroom if the toilet wasn't flushed for over an hour. Every time we came back to the room, we had to flush to get rid of the odor. The walls were also very thin; we could hear people coughing, sneezing, talking, and snoring from all sides.
Breakfast was nice enough, with some decent options available.
The gym is non-existent. In the pictures, it seemed somewhat usable, but it’s literally just one machine in a small room. The pool is also a bit small. Although the views from the rooftop are really pretty, the pool itself is tiny and feels more like a water feature than something to swim in. So it is only nice if you only want a place to sunbathe.
On the bright side, the location is pretty good. Even though it's not beachfront, it's very close—just a 2-3 minute walk to Ipanema Beach.