Casablanca 3 is a wonderful place to stay in Rio. The views are amazing and you are really close to the sea and a small beach (next to Sheraton). Also you hear the sea and waves crashing which is amazing.
Regarding location, you are 2 minutes walk to a main avenue (Niemeyer) and a bus and taxi stop. Only need to take into consideration that you are probably like 10 or 15 minutes walking to Leblon and that to get to your apartment you need to go up a lot of steps. A taxi to Ipanema would normally cost like 8 dollars.
We loved our experience and I would definitely stay at this apartment again.