After the excitement wears off, iPhone Duo’s limitations remain

Ditto the hinge, which looks great in those minimalist white-background mockups Apple is so fond of but is an obvious point of weakness, and potentially failure, for every folding device. Will it stand up to six months of folding without growing stiff, or loose, or crunchy, or breaking entirely? Will it manage three years? Apple’s pedigree when it comes to hardware design is strong, but this is a new venture in an area where the company’s engineering work is so far unproven. Apple is asking customers to take a leap of faith.

In other areas, as with the iPhone Air before it, the Duo feels like a step backwards: some compromises have been necessary in order to achieve the new form factor. They’re different compromises than those on the Air, but annoying ones nonetheless.

Most notably, Apple has dropped Face ID on its flagship iPhone, with the Duo instead relying on a Touch ID sensor embedded in the side button like the iPad mini. The last iPhone to use fingerprints for unlocking rather than facial recognition was the 2022 iPhone SE, which was not a premium device. You could buy four of those for the price of an iPhone Duo and still have enough money for two pairs of AirPods 5. It’s not a flattering comparison for Apple’s latest and greatest handset.

The Duo is also bulky to an old-fashioned extent. It’s 11.3mm thick when closed, thicker than any iPhone since the iPhone 4. At 254g it’s heavier than any previous iPhone. Yet when unfolded it’s just 5.2mm thick, which is even thinner than the iPhone Air. So you’re getting the worst of both worlds: it has the physical worries of a super-thin device, but the inconvenience of a very thick one. It’ll fit in a jeans pocket, no doubt, but it’ll be more of a squeeze than most of us are used to, particularly if you plan to put it in a case.

The camera setup is solid but, by the standards of flagship smartphones, hardly remarkable. There’s no variable aperture, since that’s an exclusive feature on the 18 Pro and 18 Pro Max. Nor is there a telephoto lens. Your optical zoom capabilities are outclassed not just by the 18 Pro, but by the five-year-old iPhone 13 Pro. (The Duo also can’t shoot in ProRAW, if that’s a priority for you, nor can it take spatial photos and videos.) Again, not a flattering comparison.

Customers are even short-changed on the color options, which are limited to the tedium of white and Night Sky, which appears to be a very slightly bluish black. As well as the default white and black, buyers of the 18 Pro get burgundy and that nice Glacier sky blue, while iPhone 17 buyers can choose Lavender, Sage, and Mist Blue. But the Duo is stuck in the same black-and-white world as the ancient iPhone 5 and the mid-price iPhone 16e.