A few remarks and recommendations on a regularly flown route, about three times a month.
You will be better off if you pick-up the A330 versus the A320/1 equipment. Even if the Business class TAM product is outdated, you will be able to benefit with sufficient head storage on the larger bird. The smaller business class cabin of the A 320/321 tend to overflow with the crew's main gear and I have seen quite frequently Business class passengers in distress over unavailable storage area.
Stay away from GRU as much as possible, as most of the flights to/from Argentina seem to end up in the airport remote area. The Bus transfer to the terminal or plane can be a dreadful experience as TAM makes absolutely no effort to differentiate their full fare paying passengers upon boarding .
GIG, on the other hand will guarantee you a normal boarding through an airport finger, albeit the same confusion at the gate. A Brazilian trait, I guess.
Food service is decent, but you never know if a printed menu will be on hand in the cabin.