Here’s a pretty interesting article about how Jimmy Fallon’s giggly nature - derided by SNL fans and early Late Night viewers as little as three years ago - is now what audiences like most about him. Unlike other late-night hosts, Fallon is content to enjoy himself, without scrambling for the funniest joke possible.
Nobody is going to accuse Fallon of being a comic genius. This is a good thing. Not being saddled with that baggage seems to make Fallon a lot more relaxed than his peers. Compared with the sweat-drenched desperation that’s so obviously apparent in Jay Leno or even the all-time favorite of comedy nerdom, O’Brien—the compulsive need to always be funny that’s alienating when the comedy isn’t working—Fallon is appealing in the manner of the popular kid in school. Yes, his good looks and confidence might make you hate him at first, but after a while, it’s just nice to be around someone who’s comfortable in his own skin.