The device pairs a passport-style 5.4-inch cover screen with a 7.6-inch inner Super Retina XDR display, runs the A20 Pro chip, and has preorders already backed up until the end of January 2027. CNET gave it 8.7 and an Editors' Choice Award, calling it the foldable that finally steals the show.

The standout is the inner display's nano-texture matte finish, the first time Apple has brought the coating from its high-end monitors and MacBook Pros to a phone.

Popular Mechanics says it resists glare and smudges better than any smartphone touchscreen it has tested, and TechRadar reports Apple used a laser to etch thousands of lens-like structures that scatter light instead of reflecting it.

Reviewers say the matte finish also plays a central role in hiding the fold crease: 9to5Mac explains it diffuses the reflected light that normally exposes topology differences on glossy panels, and CNET found the crease virtually invisible in everyday use.

First-gen Apple products are supposed to ship underbaked, but Popular Mechanics calls the Duo the exception that proves the rule, more polished than the Galaxy Z Fold8 that pioneered the same passport form factor.

It claims the Duo shows the least visible crease of any foldable it has tested, a remarkable feat for a first-generation device.

TechRadar goes further, calling it possibly the best folding hinge ever, while GB News says the phone is so refined that ten years of secret development sounds entirely plausible. All of this from a category Apple chose to enter years behind Samsung, Huawei, Oppo and Google.

Popular Mechanics reports the hinge contains more than 100 intricate components with variable resistance, opening easily partway but requiring more force to unfold fully, and closing with a satisfying click.

9to5Mac says Apple pairs this with a magnet system holding the halves shut and a Grade 5 titanium frame — the only foldable on the market with a titanium external frame and hinge cover, per Popular Mechanics.

Durability extends further: the Duo carries the same IP68 rating as the standard iPhone 17 and 18 lines, meaning water and fine-particle resistance most foldables can't match.

The 10-layer display stack uses high-strength glass above and below the OLED over a titanium plate, with a polymer coating Apple says is 40 percent stiffer than rival materials.

The trade-offs are real. The Duo drops Face ID in favor of side-button Touch ID, which CNET calls a step backward from an otherwise premium experience.

There is no telephoto camera — only 48MP wide and ultra-wide sensors — so photo capability trails the iPhone 18 Pro, though Popular Mechanics argues the trade is acceptable for the extra screen.

TechRadar adds that the right-side dock squeezes apps on the cover screen, and the phone weighs 254 grams, noticeably heavier than the Galaxy Z Fold 8.

Apple Pencil support arrives in a coming iOS update — expected by November, according to TechRadar — bringing stylus input to the 7.6-inch screen, a capability Popular Mechanics says will widen the gap with Google and Samsung rivals even further.

Apple's battery-life guidance is also realistic: reviewers got a full day of mixed use from the dual battery, and Popular Mechanics suggests keeping a pack handy for heavy big-screen days, though 60W wired charging topped 50 percent in under half an hour.

With preorders already stretching into 2027, the Duo is the most expensive iPhone ever sold, and reviewers' message is consistent — the best foldable money can buy, but not the best iPhone for everyone.