The Star Alliance Lounge Review Sao Paulo is part of the South America & Africa Points Heist Trip Report.
What do you do when you have a twelve hour layover in Brazil? The answer, if you do not have a visa, is to stay in the lounge all day. The lounge opens at 7AM and I arrived 7 minutes before that. I entered using my Priority Pass card because I did not have a boarding pass yet for my business class flight on South African. Note: If you go in the Priority Pass way, you have to pay for the shower. 
The Seating
With no one in the lounge, I was free to take pictures of all the seating and find a restful spot where I would spend my day. I settled for a lawn chair which was next to a power outlet. I slept there, semi-comfortably, for five hours after a bad breakfast.
The Breakfast
How were the eggs cold when the place just opened? That was not the way to start the lounge marathon.
The Lunch
After a bad breakfast and a long nap, I went for lunch. The lunch selection was much better. It included hot dogs, rice, curry, and pasta.
The Wi-Fi
Unlike the Priority Pass SCL, this lounge had Wi-Fi. It was very slow making me wonder how this nomad lifestyle will ever be possible.
The Shower
I had to walk to the end of the terminal to get a boarding pass in order to not be charged for a shower. After the wine tasting in Colchagua, the lounge and flight to GRU, it was worth the walk.
Overall
It’s a very nice lounge, one that reminded me of the Air China Lounge in Beijing because it is above the terminal. While breakfast was bad, everything else was good.
About a year ago, I spent the day in this lounge. Like you, I didn’t have my South African boarding pass yet, but told them at check in and showed my on-phone reservation. There’s an agent later in the day who prints your boarding pass for you, and in the meantime you have full access to the lounge and shower. I agree the food was uninspired. I lived on water, coffee and some nibbles, and enjoyed the peace and quiet til getting on towards flight times
By the time I woke up, the agent was gone! So I had to stroll down.