Jimmy Fallon’s debut as host of “The Tonight Show” had the attention of the nation’s television critics Monday night. Here are samples of what they had to say.

It is absolutely worth watching.

The premiere seemed designed to show viewers that Fallon isn’t Jay Leno or Conan O’Brien.

He is much more mainstream and at ease than O’Brien, who had the job for six months before Leno got it back.

I mean who can’t instantly love a guy who spends the first several minutes on “The Tonight Show” explaining who he is and where he come from to his new audience and also introducing his proud parents?

After doing that, he smartly started the show all over again, with announcer Steve Higgins introducing him a second time from behind “The Tonight Show” curtain.

It wasn’t long before the bit that likely was the most-talked-about Tuesday morning arrived – more than a dozen stars led by Robert De Niro walking on one at a time and supposedly paying off a $100 bet that Fallon would never host “The Tonight Show.”

Stephen Colbert, whose 11:30 p.m. Comedy Central show will compete with Fallon after the Olympics ends, dumped $100 worth of pennies on Fallon before welcoming him to the late-night competition with a word that I can’t repeat.

Then Fallon teamed with first guest Will Smith on a filmed piece – The Evolution of Hip Hop Dancing – that reminded viewers that he isn’t Leno.

U2 joined the fun, singing a tune from the 70th floor of 30 Rock, with the New York skyline aided by a beautiful sunset that may have reminded viewers the show actually is filmed at 5 p.m. or 5:30 p.m. in New York City.

Bono and the band later sat down on the couch and he and The Edge performed a musical version of the Oscar-nominated song “Ordinary Love” that brought the audience to its feet.

The success of “The Tonight Show” will be determined more by a marathon than a sprint. Fallon’s show certainly will evolve as much as Hip Hop dancing or more.

But off the first show, I’d bet $100 in pennies that the odds are that the likable Fallon will prove to be more than an ordinary love for local late-night viewers.

– Alan Pergament, The Buffalo News

So how did he do?

The Jimmy Fallon era of the “Tonight Show” officially began at midnight Monday when the 39-year-old former “Saturday Night Live” cast member walked through the royal blue curtains of a brand new set at New York’s Rockefeller Center. And then, a few minutes later, went away and started all over again.

The first entrance was devoted to thanking all the hosts who’d come before him. He also thanked his parents, who were in the audience, his mom mouthing “I love you” and his dad cracking that he’d paid a lot of money for Fallon to go to high school. Fallon reminded him it was a public high school.

The room was filled with awe, humility and comedy. And that was just on Fallon’s part. As for the audience, it was filled with obvious excitement at being part of a significant moment in TV history.

Fallon wasn’t so much nervous in his debut as he was overwhelmed by the moment.

At the same time, in just over an hour, Fallon established the tone and direction of the new “Tonight Show”: Funnier, younger, warmer, friendlier and goofier.

Good show.

– David Wiegand, San Francisco Chronicle

Fallon has long positioned himself as a regular guy, the kind who would rather play charades with his guests than engage in lame interviews – or, even better, just pick up a guitar and goof around. His likableness has taken him far.

But even by his standards, the “aw shucks” factor was high Monday night.

After a lovely opening credits intro directed by Spike Lee, Fallon took the stage, thanked his predecessors, and said: “I really don’t know how I got here.” Speaking in a voice so quiet you could practically hear audience members swallow, he introduced himself to “those of you who are watching me for the first time, which is very possible,” starting with the basics. “I’m 39 years old, I live in New York City with my beautiful wife, Nancy, and my daughter Winnie, who’s 6 months old ... and I love her so much.”

After Smith and Fallon did their hip-hop thang, the show moved to the Top of the Rock, where U2 perched along the edge of the roof against a glorious sunset, igniting cheers from the crowd and scaring the heart out of anyone with even a vague fear of heights. Back inside, Fallon chatted with Smith about fame and fear and then welcomed Bono, the Edge and the Gang for a little sit-down. After presenting Fallon with his own (red) guitar, they sang an acoustic version of their Oscar-nominated “Ordinary Love,” which sounded, as so few late-night performances do, just fabulous.

And that is where Fallon will make his mark on the show. He is the most musically inclined host since Steve Allen, with a pop-culture sensibility – he referenced both “Masters of the Universe” and “Dune” in a description of an aerial view of Dubai – to match his easygoing ways. He is playful, he is joyful and he is an astute user of social media, all of which one hopes he brings to the beloved but undeniably aging franchise.

– Mary McNamara, Los Angeles Times

What a nice young man.

Jimmy Fallon, the new host of the “Tonight” show, introduced himself to viewers Monday like a freshly licensed doctor taking over a retiring gerontologist’s practice.

Fallon’s debut was more sweet than sassy. He was the grateful heir, the eager freshman, the class clown with top grades and a good heart – someone older viewers can embrace without fear of being mocked or overlooked.

And that was interesting, because the most fateful generational shift isn’t between baby boomers who were loyal to Jay Leno, the previous “Tonight” host, and younger viewers who are more comfortable with Fallon, a “Saturday Night Live” alumnus who incorporated tweets and Internet skits when he took over “Late Night” in 2009. Now it’s “Tonight” vs. tomorrow: This old-fashioned kind of programming is at the mercy of a changing landscape where audiences are balkanized and viewing habits are radically altered.

The “Tonight” show is in good hands, but its longevity rests less on the host than on audiences who increasingly don’t turn on a television to watch television. Fallon intimated as much when he recalled begging his parents to let him stay up late to watch Johnny Carson. He got a little emotional when he added that he hoped there was “a kid out there asking their parents to stay up to watch me.”

Maybe. But that kid can watch “Tonight” on his iPhone on the school bus the next day. And unlike Fallon, he isn’t likely to grow up aspiring to host the “Tonight” show anymore than he will get his news from a paper edition of the New York Times.

Paradoxically, a format that hasn’t changed since Carson codified it (monologue, celebrity, musical guest), is ideally constituted for the cut-and-paste ethos of YouTube and Twitter. Far more than a drama or a reality show, a joke or musical number can be plucked and posted online as a stand-alone. There is no need to DVR anymore: why record the cow when the Internet and social media can give viewers the milk for free?

And that sense of impending change tends to trigger the instinct to preserve, which may be why Fallon’s first “Tonight” show was so steeped in tradition and solemnity.

Fallon is a charming and gifted comedian who on his first night chose to be subdued and at times even serious. That said as much about the uncertain future of “Tonight” as it did about its new host.

– Alessandra Stanley, New York Times