A. J. Black’s review published on Letterboxd:
One of the most infamous and well-documented James Bond movies, Thunderball really is a film of two halves. On the one hand, it's perhaps the most quintessential template of a Bond movie we've ever had; Sean Connery in his prime, some of the most truly glamorous girls and locations in the series, and one of the biggest and most outlandish plots of any such film. On the other... the script fails to shade in our villain or main love interest nearly enough while the pace slows to a crawl at numerous points. It might frequently be the most elegant, poised Bond film - but at times, it's also one of the dullest.
I've read about Thunderball at length; so much went on behind the scenes making this film, you could make a movie itself about it (in the alternate life where I produce movies, I've optioned Robert Sellers' brilliant The Battle For Bond about this conflict I can't recommend enough). The end product is memorable in so many ways, plenty of them positive - Connery remains on form, imbuing Bond as ever with a cool, calculated style and menace no successor has ever truly bettered (to date), we get one of the best themes courtesy of Tom Jones (and this also happens to be perhaps John Barry's best score after OHMSS), the narrative is easily the greatest threat Bond has ever faced and truly does SPECTRE justice (it's their defining story really), and the girls are as exotically stunning as they've ever been (Luciana Paluzzi in particular is utterly gorgeous as Fiona Volpe, one of the best Bond femme fatales you probably don't remember) while the Bahaman locations that primarily make up the film are beautifully rendered by director Terence Young, who again gives the film a class and elegance as he did with FRWL. The problems, ultimately, come from the script - Adolfo Celi's villain Emilio Largo looks every inch the part, an urbane, chilling eye-patch wearing presence, but he fails to loom as large as a Goldfinger or truly deadly as a Red Grant, thereby swiftly becoming forgettable thanks to underwriting; while the plot too often indulges the producers love affair with filming underwater and though it's superbly achieved by Young (the final harpoon battle still holds up as impressive nearly 50 years on), it cripples the pace - this could easily have been 20 minutes shorter, making a punchier film.
It's a shade better than Goldfinger as it holds a level of brawn, scope and depth to its narrative and characterisation (such as Domino's arc), but Thunderball in the end falls short of being up there with the best of Bond. At times it's a terrific picture - its glamour, production and acting are hitting heights new to the series, but it so often lets itself down by dragging the story, being arguably too long and underwriting several crucial characters that deserves more shading. Frustrating as, in some respects, Bond has never been better.