I have stayed at Marriott’s all over the world. Like all Marriott's, the people were great. Unfortunately, the facility was lacking. The toilet seat test is one that I give upon arriving at a new hotel. The Copa failed miserably.
The facility is new (by Rio standards) but retains some of the old-world looks. You are better off eating at one of the churascos or sidewalk cafés. One recommendation is Top Beer, a sidewalk café located just north of the Palace Copacabana, where Julie and I were treated like visiting royalty.
A word to the wise, the American Express office is located near the Palace Copa but is closed on weekends. Be careful at ATM's. The AE office would have been great if it had been open.
All in all, Rio is a wonderful city, but now it’s time to board the Oceania Insignia and head for the Amazon.