Cramer is an entertainer who is about 40% right. That means that flipping a coin, or just doing the opposite of his recommendation would result in better returns. That said -- he's honest. He tells you to do your own homework and to listen to nobody including himself.
As for NRGY, I think he is right on this one, and I'm a buyer on this weakness. I'm investing long term and looking for high dividends and stable long term industries. NRGY fits the bill perfectly.
Cramer made $398,000 for charity in his charitable trust in 2010. I'd say he is pretty good. I've made money by following along with some, not all, Action Alerts holdings and gotten quite an education by watching how Cramer operates (under some considerable restrictions.) You have to pay attention to timing and catalysts for stocks he talks about. You can't just buy and expect to make money. And you have to handle losses as well as gains smartly. He isn't right all the time.