I have to say, the Exp. Share is so wonderful. Right now, I'm doing a playthrough where I have a full team from the beginning of the game. This would be difficult to do without a lot of grinding if it weren't for it. Also, since I tend to just use my Persian (and she keeps using Pay Day, which is why I am very rich right now), the rest of my team would be severely underleveled. Instead, they are only a few levels lower, but tend to be more useful in Gyms, which makes up for it. And I'm within normal levels for the game.