The iPhone Duo Reviews Are In: It Runs Warm, the Hinge Holds Up, and the Inside Camera Is Rough

This morning we told you there will be a few iPhone Duos to walk in and buy on Friday. Since then the reviews have been landing all day, which is the better guide to whether you should want one. The short version: Apple’s first foldable is fast, fun and unfinished. It also runs warm.

The Verge’s Nilay Patel and Allison Johnson summed it up best, as MacRumors quoted: the Duo is “expensive, it’s full of compromises, and it can be incredibly frustrating to use.” They also called it fun “in the way the best early adopter devices are fun,” and compared it to the first MacBook Air, a product that took a full redesign to get right.

It runs warmer than an iPhone 18 Pro

Heat was the biggest theme across reviews, and opinions differed on how much it matters, per MacRumors’ roundup.

• The Wall Street Journal’s Joanna Stern said the back got warm during FaceTime and taking photos, and she ended one FaceTime call early because of it. Apple told her the warmth is the thermal design moving heat away from the chip to keep performance up.
• The Verge said the phone heats up with long camera sessions, especially with both displays on for Duo Preview, and “gets hot enough to start noticeably lagging after a while.” It also flagged heat with some third-party video apps and Google’s apps.
• HTX Studio ran a 30-minute gaming test. The Duo hit 46.5°C, compared with 43.8°C for the iPhone 18 Pro and 43.2°C for the Pro Max. It also ran about 20 percent lower frame rates and couldn’t hold 300 nits of brightness, dropping to 185.
• Tom’s Guide measured a 75.9 percent 3DMark stress-test stability score, between the iPhone 18 Pro Max (79 percent) and Samsung’s Galaxy Z Fold8 (72 percent).
• 9to5Mac said the Duo runs “a bit hotter” than the iPhone 18 Pro, “but not in a way that impacts performance.” Gizmodo said its vapor chamber “does a solid job” of preventing slowdowns.

The Duo uses the same A20 Pro chip as the iPhone 18 Pro, but with a thinner vapor chamber. Apple added a flexible graphite pipe through the hinge to move heat between the two halves, according to MacRumors. In everyday use, Gizmodo’s Geekbench scores were nearly identical to the 18 Pro. The heat shows up under sustained load: gaming, long video calls and extended camera use.

The hinge survived 32,000 folds

Apple hasn’t published a fold rating the way Samsung does. So Stern built a machine and folded her review unit more than 32,000 times over four nights, MacRumors reported. A push-pull gauge showed the hinge was actually slightly stiffer afterward, and Stern said it “felt pretty much the same as day one.”

There are caveats. The test was done with a case on, and the machine didn’t close the phone all the way each time. Stern also didn’t say whether the crease became more visible. Samsung, for comparison, says the Galaxy Z Fold7’s display passed a 500,000-fold test. One reviewer’s rig is encouraging, but it isn’t a durability rating.

The inside camera is the weak spot

The Duo’s inner screen hides an under-display FaceTime camera, a first for an iPhone. According to MacRumors, Gizmodo said it’s a 4-megapixel sensor and called its photos “low-res, washed out, and just not sharp at all.” Marques Brownlee called it “very first gen” and the photo quality “trash.” Reviewers said video holds up better than stills, and that the camera disappears when you’re not using it.

There are good workarounds. The outer screen has a regular 12-megapixel front camera. PetaPixel noted you can unfold the Duo and use the outer display as a viewfinder to take selfies with the much better rear cameras.

The good news

• Battery: In Tom’s Guide’s web-browsing test, the Duo lasted 13 hours and 20 minutes. That’s well behind the iPhone 18 Pro Max (17 hours, 31 minutes) but ahead of the Galaxy Z Fold8 (10 hours, 6 minutes).
• Apple Pencil is coming sooner than promised. Creative Strategies analyst Max Weinbach said Apple Pencil (USB-C) works on both Duo screens with the iOS 27.2 release candidate, MacRumors reported. Apple had said Pencil support would arrive before the end of 2026. iOS 27.2 is expected next week.
• The outer screen works as a real phone. CNET’s Abrar Al-Heeti said the 5.4-inch cover display “doesn’t feel cramped” for texting, email and quick tasks.

The annoyances

• Apps aren’t ready yet. WIRED’s Julian Chokkattu said many third-party apps are still letterboxed on the 7.6-inch inner screen, and suggested waiting “a few months” for developers to catch up.
• Touch ID takes getting used to. 9to5Mac’s Chance Miller called switching from Face ID the hardest adjustment, and said turning on Apple Watch unlock helped a lot.
• Some MagSafe stands won’t hold it open. Mrwhosetheboss showed an unfolded Duo tipping on an upright charger because the MagSafe ring sits on one half, per MacRumors. The Verge’s Patel charged one horizontally without trouble, so it depends on the stand.

What this means

• If you have a preorder, nothing here is a reason to cancel. The issues reviewers found are first-generation trade-offs, not defects. Install iOS 27.2 when it arrives next week to get Pencil support.
• If you game or take long video calls, expect warmth. Mrwhosetheboss found the Duo traps more heat when closed, and The Verge saw the biggest slowdowns with both screens and the camera running together.
• Use the rear cameras for selfies. The inner camera is fine for FaceTime, but not for photos you care about.
• If you’re on the fence, waiting is reasonable. Delivery dates already run into January, and app support should be much better by then. That’s what WIRED recommended.