Bridget Jones's Baby, says the Mirror's David Edwards, is "a laughathon" that fans should "watch at all costs".
Renee Zellweger plays Helen Fielding's perennial singleton for the third time in the film, which this time sees its scatty heroine become pregnant.
Zellweger joined co-stars Colin Firth and Patrick Dempsey at Monday's launch.
The pair play romantic partners of Zellweger's character, either of whom could be the father of her unborn child.
Emma Thompson and pop star Ed Sheeran also appear in the film, which is out in the UK on 16 September.
According to The Guardian, Bridget Jones's Baby is "a better Bridget than the last movie" - 2004's Bridget Jones: The Edge of Reason.
It is, Peter Bradshaw's review continues, "something resembling a likeable, good-natured one-off TV holiday special".
Jamie East in The Sun writes: "The third in the Bridget Jones series has everything we love about her films.
"Nearly all the cast is back, jokes are razor-sharp and cultural references are on point."
One notable absentee is Hugh Grant, who chose not to reprise his role as the caddish Daniel Cleaver.
His absence, says Variety's Catherine Bray, "is certainly felt" in "a mixed bag" that "doesn't quite hit the heights" of 2001's Bridget Jones's Diary.
"Depending on which side of the age divide viewers fall, Bridget Jones's Baby will either be viewed as charmingly retro or irredeemably irrelevant," writes Screen Daily's Fionnuala Halligan.
The film, she continues, "works best as a nostalgia piece, to help viewers recall where they were in the late 1990s when the world thought it was charming for a woman to be so prettily inept".
Meanwhile, Leslie Felperin writes in The Hollywood Reporter: "There are crisply folded lines, and pleasingly peppery performances from the supporting cast."
But she goes on to suggest "there is a splinter of ice... where its beating heart should be" and that "no-one involved is really doing this for that much love".
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The new Bridget Jones film has received a warm response from critics following its world premiere in London, with one naming it "the funniest of the series".