We were booked into this hotel at the end of a cruise around South America. We were travelling with friends.
The hotel is on the seafront on Copacabana beach. It is handy for the beach and for restaurants. The staff were pleasant
The public areas of the hotel are clean and fresh.
The rooms that we stayed in were horrid.

We had ants in our room. To be fair they were dealt with immediately, but even though there was a language barrier we had no difficulty explaining the problem; It was obviously a regular complaint.
We had a balcony, but the tiles were broken and the door on to the balcony had a 2-3cm gap underneath. We were concerned that the traffic noise might keep us from sleeping. We need not have worried as the roar from the air-con drowned it out.
We had a leak in our bathroom, which they stopped, but we then had no cold water for a day.
There were no net curtains or voiles at the windows and the rooms were overlooked. So unless one wanted to undress in public, the curtains had to be drawn to change clothes.
The room was dark and the lighting inadequate.
The friends we were with had a cockroach in their room. and a large area of damp from the shower on the other side of the dividing wall. They asked to be moved, but the room that they were offered was smaller and had similar problems.
Another friend said that she had black mold in the bathroom (though I didn't see this myself).
The bedrooms were musty and the drapes smelled of tobacco as did the bed covers, though the sheets were clean.
We complained to the tour guide, but he just shrugged and said that they were renovating the rooms but obviously had not done ours yet.

I would not stay there again.

The Windsor Miramar Palace Hotel is a traditional hotel in Rio de Janeiro, established in the 50's. I stayed there several times in 2009. Like many other places there are pros and cons. The staff was very friendly and helpful at every opportunity, the cuisine is very good as well, rooms are spacious with an awesome view to the beach... However, most bathrooms are in need of a reform (those old bathtubs are simply disgusting and they don't smell good).

The staff was very helpful and accommodating. The breakfast was excellent and its location on the beach was ideal for beautiful views. However, the neighborhood is a bit overrun and the room itself was quite inadequate. There were ants in the room and the internet was spotty and slow. Most of the rooms had a balcony off the side of the building with a pretty view of the ocean. If the rooms were cleaner and remodeled, then it would be much nicer place to stay.

I stayed at the Miramar Palace Hotel (aka “W”—I think for Westin) for three nights as part of a Tourlite International group tour. The tour group (which I would not recommend) selected the hotel. The tour guide reiterated daily how wonderful and sought after this hotel was. I think she was trying to convince us that we were actually in a place that was respectable when the reality was that this hotel is comparable to a Motel 6, at best. The view of the beach was ok and the breakfast was pretty good. When you take away those two factors this place is a complete and utter dump. There are little ants crawling all over the room and in every room. The sheets are dirty and pillows smell of nothing good. The bathtub and shower curtains smell of mildew. The hotel does not offer an iron so don’t expect to smooth out those wrinkles after a long flight. You’ll have to go out as you are. Bring your own washcloth or bath sponge. The hotel does not provide washcloths. There appears to be much better options in Copacabana, Impanema or Leblon. Search for hotels in Impanema or Leblon before you opt for a hotel in Copacabana. I also did a search of Tourlite after my trip and the packages they offer on their website do not include this hotel. This is an indication that they do not use Miramar Palace Hotel on their standard trips. I have no idea why they placed us in a hotel that they do not advertise but I fault our travel agent for not doing research in advance. You are spending good money to travel and if you want to enjoy your trip stay away from this place.