The 71-year-old's show was "perfectly pleasant", said The Times' reviewer, but was "not full of the sort of comic vitality with which he made his name".
The Daily Mail said the ex-Monty Python member had become "rueful - even, in the true sense of the word, pathetic".
The Alimony Tour - so-called because Cleese says it is funding a divorce - opened in Cambridge on Tuesday.
Comedy website Chortle said Cleese was "pleading penury" and had been "forced out on the road to scrape together a living when he'd rather be at home with a good book".
As such, it continued, there was "a slight feeling that with the flagrantly money-making Alimony Tour that he's done just enough to get by".
It described the Corn Exchange gig as a straightforward re-telling of his rise to fame, full of anecdotes he had polished in interviews over the years.
"He hasn't even bothered to learn the script, reading his lines from a none-too-discreet autocue," its correspondent claims.
The Independent's Julian Hall gave the show three stars out of five, saying fans of his classic sitcom Fawlty Towers were "in for a treat" because of clips that feature during the show.
Yet The Times' Dominic Maxwell argued there were too many such clips, and "too little of Cleese developing intriguing ideas about craft".
He gave the show two stars out of five, describing it as "a lecture tour more than comedy tour" that was more "intelligent" than "wildly funny".
His sentiments were echoed by Quentin Letts in the Mail, who said his routine was "initially funny" but peaked after 20 minutes.
"The audience tries to jolly him along, but the fizz has evaporated," he wrote. "Topical satire has yielded to autobiographical dribble."
After his last Cambridge date on Saturday, Cleese will perform his show in several cities across the UK before closing the tour in Bath on 2 July.
Speaking to the BBC in January, the Somerset-born star said the show would be "a fan show" that would steer clear of London's West End.
The opening night of comic actor John Cleese's first UK tour has been met with lukewarm reviews by critics.