One of Roger Ebert's strengths is that he knows just what he's doing: reviewing movies. He doesn't take himself too seriously, because he knows that his job isn't one of the world's genuinely important ones. So he takes the opportunity to explain his star rating system in a review:
Shaolin Soccer, a goofy Hong Kong action comedy, gets three stars. It is piffle, yes, but superior piffle. If you are even considering going to see a movie where the players zoom 50 feet into the air and rotate freely in violation of everything Newton held sacred, then you do not want to know if I thought it was as good as Lost in Translation.
Exactly. Sure, Leaving Las Vegas is a "better" movie in objective, intellectual terms than Rumble in the Bronx. Duh. But how a movie rates depends on what kind of movie it is. If you want to have fun, watching Nicolas Cage drink himself to death while Elisabeth Shue is raped by vacationing frat boys is probably not your best choice. Better to watch Jackie Chan disable a rampaging hovercraft with a giant blade stuck through the door of a commandeered sports car.
Similarly, if you want to understand something about the human condition, Star Wars won't tell you much. Except that you can walk out of a theatre feeling a lot better than when you went in. Four stars? Yup.
In another example of not taking yourself too seriously, Wired News notes that:
If you take a close look at the form Google filed with the Securities and Exchange Commission, the exact value of its planned offering is $2,718,281,828 dollars, which some would immediately recognize as the mathematical constant e.
Actually, it's e times a billion, rounded off to the nearest dollar, but close enough. Four stars to Google for putting an Easter egg in a stock offering.