I stayed at the Sao Paulo Renaissance Hotel last year for 10 days and I would have to say that it was a very positive experience. When I was there in April 2010, they were in the process of remodeling the lobby.
The room I got was nice. The concierge level was excellent, probably one of the best I've experienced after the Melbourne Marriott, closely followed by the Berlin Marriott. The breakfast and evening appetizers were good the basic alcoholic drinks were included.
The location of the hotel is ok. Its very close to a metro station which is a major plus. However, from a dining perspective, its not located close to Rua Oscar Freyre, which is where the most fine dining and exclusive boutiques are located. Basically, you can walk (downhill) to Rua Oscar Freyre and it will take you 15 minutes to reach this place. However, returning by feet is another story since you will be walking up the hill. I think that you are better off taking the taxi.
The staff at the hotel is very friendly and the girls working at the concierge desk are very knowlegeable, not to mention, quite pretty!!!. Overall, this is a very excellent hotel.