Yes, baseball lends itself to instant replay, because there are a lot of cameras and a lot of breaks in the game. Because baseball happens slowly, the game doesn't need to be stopped in order to check on a previously play. There can be a lot of replays in the game without obstructing the ultimate flow of the game.
It is bad because it takes longer and it costs more money. The tickets will have to be more money. I hate it and I think this should not happen. The mlb says that it would expand the "reviews". I don't think it is a good idea at all so if you are looking at this please say no.