TV critics have described Nigella Lawson as the “icing on the cake” of The Great British Bake Off, after the show returned for a new series on Tuesday.

Lawson has replaced Dame Prue Leith, who announced she was leaving earlier this year after nearly a decade in the programme’s famous tent.

The Telegraph said Lawson gives the Channel 4 series a “new lease of life”, while Digital Spy agreed she was a “brilliant addition” to the line-up.

But the Independent was cooler on the launch episode as a whole, saying the show “wastes Nigella’s prodigious charms and misses chance for a true revamp”.

The return of Bake Off saw Lawson join fellow judge Paul Hollywood, who has appeared on the programme since its launch in 2010, and presenters Alison Hammond and Noel Fielding.

Former Bake Off winner Giuseppe Dell’Anno told BBC Radio 4’s Today that Lawson “did produce a step change” to the show and was a “nice fit with the ethos of the programme”.

“She was doing her best by capturing the vibes of a cake, the feelings, what it makes you think of, which was very nicely balanced by Paul being very technical and scrutinising,” he said.

“I think, however, that she will get better over time, because my gut feeling yesterday was that she was still in new territory.”

In a five-star review, the Guardian’s Lucy Mangan, external said Lawson “moves through Bake Off dispensing words of wisdom, generous praise and gentle criticism”.

She added that Lawson is “just as confident as Leith but a much quieter, more soothing presence that works perfectly with Alison Hammond’s ebullience and Paul Hollywood’s teacher-ish vibe”.

The Telegraph’s Anita Singh, external also awarded five stars, remarking that “Bake Off and Nigella are a match made in heaven”.

“She brings glamour, intelligence and poise. And, of course, a hefty dollop of innuendo,” Singh said.

“Lawson is supportive in her judging but not afraid to tell the bakers where they can improve. She gives helpful advice.”

The launch episode was described as “one of the most disastrous openers ever” by Metro’s Adam Miller, external – but luckily he was only referring to the cakes.

“When Bake Off should be crumbling after 17 seasons, Nigella Lawson is making Channel 4’s crown jewel fresher than ever,” he said.

“It’s clear to see she is the lifeline Bake Off needed to ensure it could easily have another decade or more in it yet.”

However, other critics said Channel 4 had missed an opportunity to revitalise the programme.

Awarding two stars, the Independent’s Nick Hilton, external said Lawson quickly “feels part of the fabric,” adding: “But this is also the problem. The Bake Off format is very tired.”

He wrote: “The cakes wobble, the decorations melt, the bakers over-salt the batter, and everything remains the same.

“Nigella’s arrival might have been an opportunity for a harder refresh. But instead of bending the format to suit Nigella, the new judge bends to the will of the programme.”

Hilton acknowledged that producers “might have done brilliantly to snag Nigella, and it will undoubtedly lead to an uptick in viewers”.

“But they’ve applied her prodigious charms too thinly, and even she – with her preference for all things ‘sumptuous’ – can’t stop the feeling that the show has gone more than a little stale.”

Several critics noted that Lawson did not deliver as much innuendo as expected during her debut in the tent.

“Add Nigella – famous for her on-screen coquettish eyelash-fluttering and cheeky language choices – into the mix, and you’d imagine the sauciness gets dialled up to 11,” said the Radio Times’s Jane Rackham, external.

“Instead, she’s cut back on the sauce. She makes well-informed and helpful comments about the amateur bakers’ efforts.”

Digital Spy’s Janet A Leigh agreed, external, noting: “As is the nature of Bake Off, there were many opportunities for Nigella to engage with the playful, flirtatious nature that has underpinned the show since its inception. Yet every opportunity was gently rebuffed.”

Instead, she said, Lawson “has a way of talking about food that celebrates it and expands the audience’s understanding of flavours without seeming pretentious.

“If episode one is just a flavour of what to expect from Nigella, then it is hugely encouraging. She cares deeply, steers wisely, and slots effortlessly into the close-knit team.”

When Lawson was faced with innuendo-laden comments from contestants or co-stars, she often “wisely said nothing”, noted the Daily Mail’s Jan Moir., external

“Ultimately this was a tremendous debut performance from the new mistress of meringue, showing a side of Nigella we have not seen before: quirky, commanding, funny – but also humane,” she concluded.

Ben Dowell of the Times observed, external: “Bake Off has always been one of TV’s more beguiling offerings with a comforting romance about it.

“It’s not perfect. Hammond is ebullience and warmth personified but her co-presenter, the erstwhile Mighty Boosh comedian Fielding, still looks a bit lost, as if he has wandered in from the wrong set.

“But with Nigella the show is definitely in safe hands. Bake Off has found a new star.”