The hotel is in a very good area, quite close to Avenida Paulista, where you can easily get the tube or buses.
Breakfast is very good, with many variaties and all the attendants are very kind and helpful.
The only 3 bad points were: the swimming pool/ sauna area was quite desert and did not look very confortable (the swimming pool is very clean and with a good view though, just looks cold); the shower area inside the room could be cleaner; there is a construction site beside the hotel, but they only start working after 8am and the hotel sound isolation is very good if you have the windows closed.

Excellent service in a well located hotel. Specially great for short stays in São Paulo, since it´s reasonably close to all main attractions.

I stayed at the Mercure Stella Vega in December 2011 for business. I thought it was a very good value product.

The highlights are as follows:

-Rooms were reasonably priced for the space, amenities (breakfast, free internet).
-Good amount of space in the rooms, in addition to the bedroom, there was a sitting area space with a desk and chair. This was great for working after hours and having separate space to work and relax.
-All of the front desk staff were extremely courteous, helpful and trilingual. One of the staff members went out one block to get me a taxi in the morning.
-Approximately close to Faria Lima (15-20 taxi ride).
-I was on the 13th floor, and had a great view in two directions.
-The breakfast room/restaurant was adequate, I had breakfast from a large buffet spread each morning and the dinner/lunch options were fine.

While I am not accustomed to typical SP prices (and am comparing this to NY and London hotel prices), I thought this was a great value and I would stay here again.

The only drawback may be that I'm not sure how much retail is walkable form the hotel.

The hotel is located near the Ibirapuera Park. That means you're gonna need a cab to reach almost every tourist or business related site in Sao Paulo. The neighborhood of this hotel isn't nice, it actually gets pretty scary in the night. However, if you leave the hotel and walk to the left some blocks away, you'll find nicer streets, with some shops, restaurants and pastry stores.
The room is old, but very big. It has a living-room, with a desk and an armchair, and the room itself, with the wardrobe and the bed, separated by a sliding door. The tv set is the conventional old one, with a tube, and most of the cable channels were unavailable. The floor is paved with carpet, which I don't appreciate much, but it seemed clean. The bed is huge and comfy, so are the sheets. There´s no central air conditioning, instead you'll find a domestic-like device placed onto the wall (although it is the split one, it's still kind of noisy). The wi-fi is free and stable. The bathroom is ok, the amenity kit is very good and I liked the magnifying mirror. One complaint I have is that the housekeeper never minded to replace the handkerchief package when it ran out on our first day there (we stayed for more two days). I didn't try the breakfast buffet, so I can't comment about that. This Mercure Hotel has a lower rate, so you'll get what you pay for