"The one thing you can say for certain about Twitter is that it makes a terrible first impression," wrote Steven Johnson in his TIME cover story on the micro-blogging site, and it's true: you'll either love it or hate it. Haters maintain that nothing worth saying can be said in 140 characters. Lovers quote Hemingway's most famous short story in its entirety: "For sale: Baby shoes. Never worn." Nevertheless, Twitter's ubiquity is upon us, and at least the musings of Twitterati like Ashton Kutcher and Shaquille O'Neal are less harmful than their movies.