Saturday Night Takeaway spin-off leaves US critics unimpressed

The show sees Neil Patrick Harris (right) mentor a pint-sized look-alike

A US version of Ant and Dec's Saturday Night Takeaway has received a lukewarm response from critics, with one calling it "more exhausting than entertaining".

How I Met Your Mother star Neil Patrick Harris hosts the NBC show, which has been renamed Best Time Ever.

But the mixture of stunts, sketches and celebrity cameos was "forced and frantic", according to USA Today.

The Wrap agreed, saying the show's premiere, featuring Reese Witherspoon, was "not as fun as advertised".

"A weekly variety series with Harris as its giddy, self-mocking ringleader is a brilliant idea," wrote its critic.

"But Best Time Ever has been overly optimistically titled."

Former Pussycat Doll Nicole Scherzinger served as Harris's sidekick on the first show, which also featured an appearance from singer Gloria Gaynor.

The show also featured a junior Harris look-alike called "Little NPH", similar to the "Little Ant and Dec" characters from the UK original.

Anthony McPartlin (left) and Declan Donnelly are among the show's executive producers

Variety's Brian Lowry said Tuesday's show "yielded an energetic but slightly headache-inducing hour" that lacked "any consistent sense of spontaneity".

"The episode only sparked to life when Harris and guest announcer Reese Witherspoon engaged in a climbing stunt," he continued.

According to the Hollywood Reporter, the first show "did not come close to fulfilling its promise of being the best time ever".

"Perhaps some notes in modesty needed to be taken from the title of the original series," its critic went on.

Ant and Dec travelled to New York to see the first show being recorded and have been pictured on social media drinking celebratory pints on the set.

The British pair are among the executive producers of the US version and had previously pledged to be "heavily involved" in its production.

Harris, 42, is a popular actor and personality in the US who appeared on Broadway last year in Hedwig and the Angry Inch.

Yet his recent stint as host of this year's Academy Awards ceremony was much criticised, and even Harris himself questioned whether he would ever be asked back.