Having regularly flown in and out of Sao Paulo over the last few years it's noticable how busy the airport is getting, and how it now suffers from overcrowding during the peak periods.
There are only two terminals, but it feels like there's just one as both terminals are joined end on end, which basically turns both terminals into one long building.
When you depart the immigration immigration process can be slow, especially during the evening when most international flights depart, and arrival immigration is usually extremely slow especially during the morning - and the air con is ofren inadequate, making a very hot environment.
The airport lacks comfortable seating areas and the few restaurants available are overpriced, even by international airport standards.
When you travel back to the airport make sure you allow plenty of time, especially during week day rush hour and from lunchtime on Friday when there's a mass exodus from the city to homes in the country or on the coast.
A useful company providing taxi from Sao Paulo Airport is Sao Paulo Airport Transfers (saopauloairporttransfers.com). Unlike a lot of companies they'll monitor your flight arrival so the driver is always waiting, even if your flight is delayed. If you're getting a taxi back from your hotel then they'll generally notify you if you haven't allowed enough time due to traffic conditions etc and arrange to pick you up earlier.