We had a great time at Julios place in central Copacabana during Carneval season! The location is great and the room / bathroom very clean and nicely furnished. He helped us out with any problems we had and was a very warm & welcoming host!
2 things to know in advance: the bathroom/ shower is shared with another guest room and Julio and there are quite a few house rules, most of them should be common practice though :)
We definitely recommend Julios room to anyone seeking a great stay in Copacabana!