I'd get it on PC but most of my friends play PS3 so if we wanted to play say TF2 together we couldn't
I heard the HL2 games had problems on PS3 but may have been patched. No idea about how TF2 and Portal perform. If you're only interested in TF2 then I'd recommend convincing your friends to switch to PC, since it is free to play on there. Otherwise I still consider Orange Box to be the best bargain ever in gaming so I wholeheartedly recommend it.