However, another commentator says it has "just the right level of poignancy".
M&S's campaign film (see end of article) opens with Paddington Bear asleep on Christmas Eve. However, a dream about marmalade is interrupted with a thud. He stumbles across a present thief, who he then helps re-deliver a sack of stolen presents.
The film had racked up close to two million views in four hours on the Marks & Spencer Facebook page, and has been watched more than 250,000 additional times on YouTube.
According to social media monitoring tool Brandwatch, 97 per cent of mentions about the campaign on social media have been positive. The audience for the campaign was more than two-thirds female, Brandwatch's analysis shows.
M&S takes swipe at John Lewis
M&S also created #LoveTheBear, a hashtag complete with its own bespoke paw print emoji. The retailer used this to take a swipe at rival John Lewis after its rival launched an apparent teaser for its Christmas ad with the hashtag #UnderTheBed.
But what does the PRWeek Christmas panel think?
Emma Hazan, global head of consumer at Hotwire, said: "The M&S ad is all a bit perfect, isn't it? From the Christmas decorations in each house to the beautifully diverse family seen opening their presents with delight - wherever you go it's a very M&S Christmas but with Paddington Bear and a thief-come-good. Not exactly reality for most people but a nice escape from the norm and does make you feel all Christmassy... but then a bit cringey at the same time. John Lewis should not be too worried."
James Herring, managing partner at Taylor Herring, thinks film distributor Studio Canal will benefit most, following the campaign's tie-in with the feature film Paddington 2, which is being released in the UK on 10 November.
Herring said: "Putting the charity link to one side - the mega-media spend brand partnership is a marketing coup for the moviemakers and will keep 'Brand Paddington' front of mind with cinema-going families in the run up to Christmas. Naturally, though, both partners will benefit from in-store merchandise sales."
Nik Govier, co-founder of Unity, added that the M&S campaign had "just the right level of poignancy and will sit well with Britain's post-Brexit battered family audience".
She said: "They've pulled off an ad that feels both Paddington and M&S in equal measure and also feels natural. Tying into an existing independent character isn't new, but the timing of this ad - hitting just before the film's release - is perfect, as both campaigns will benefit from each other's marketing, giving them exponential power."
David Fraser, founder of Ready10, said: "One of the questions before Christmas ad season began was whether any retailer would be going with a "blockbuster" campaign and M&S have certainly delivered. Unlike the other ads unveiled this week, this is low on product and all about storytelling, with a little bit of everything wrapped up in the tale - morality, fantasy, comedy, the baddie seeing the error of his ways...and of course a happy family opening their Christmas presents.
"The irony is that bar a strap at the end it doesn't mention the M&S brand once whilst featuring a plethora of Paddington messages, even including the 'in cinemas now' line."
Fellow panelist Ranj George, UK head of consumer at Lewis, added: "The sentiment behind the ad does give a real feel-good factor, and the addition of Paddington Bear to help tell the story not only plays to adults and children alike, but has the added benefit of providing some topicality with the imminent release of the new Paddington Bear film.
"Beyond that, though, it doesn't have the same emotional resonance as previous years' John Lewis ads, for example, so I don't believe it will be an ad we will be talking about in a year's time."