I took 5 flights during last year's WC, 4 with GOL (including CGH-SDU) & one with Azul. All flights were perfectly fine, just like any flight here in the US. Azul's plane was newer with all the bells & whistles (usb, widescreen, etc). GOL is similar to SouthWest here & they're most likely the cheapest you're going to find. BTW, there's a tourist bus right outside the SDU airport. It's clean, safe, and cheaper than a taxi. Also, the driver will stop almost anywhere you want along Copacabana or Ipanema.