I felt the Gen 3 Berries were very useful; especially the Lum (alleviates status conditions) and Leppa Berries (restores the PP of moves). RSE Contests were the best incarnation, IMO, that the developers have produced so far. I just wish that the Contest Condition influenced by the PokeBlocks was somehow reversible...
The berries that boost stats in a pinch are awesome, except the suckish part is that a lot of them are hard to obtain in Generation 3, such as the Speed-boosting Salac Berry. The EV berries are freakng awesome as well, in case one makes a mistake while EV-training Pokemon.