The very nature of the iPhone Duo raises numerous obvious questions about what it’s like to use. Does it not feel thick and heavy, awkward both to pocket and unpocket? Doesn’t the outer (cover) screen feel small and cramped, with an unfamiliar squat-rather-than-tall layout for UI controls in every app you use? Isn’t it weird that when you open it up to use the inner screen, that all the hardware buttons on the edges of the device are in the “wrong” places for a tablet? For anyone who’s gotten used to Face ID over the last decade, is it not frustrating to go back to Touch ID? And what about third-party apps that haven’t been updated to support the Duo’s novel displays — do they not suck to use?

Clearly, the point of a Duo review is to answer these questions, which really boil down to one question: How did Apple solve these problems?

The answer is: They didn’t.

All of these problems are real, and each of them detracts from the experience of using the Duo. Some of them have been mitigated through thoughtful design and clever engineering. Some of them might be solved in future iterations of the device. Some of them, though, I believe are endemic to the very idea of a foldable, and cannot be solved.

The Duo name is perfect. It truly is like having two devices in one. The outer device is, by far, the worst iPhone Apple has ever made. It’s a miserable fat little thing. The inner device is a splendid, joyful, beautiful tablet, with a UI that out-iPads the iPad. For me, by far, it’s my favorite tablet experience ever. I prefer it to any iPad or Kindle-like reader I’ve ever used.

So I’ll cut to the chase. The decision of whether you might want to buy a Duo is not easy, because only one of its two selves is good. You might be delighted, despite its clear compromises, if what you value most is a pocketable small tablet and are ambivalent about your iPhone. You might be endlessly frustrated if you love your iPhone, and use it extensively, often for quick interactions throughout the day, every day.

More Than Meets the Eye

I was a kid when Transformers hit the toy market. I had a few — every boy my age did — but I was more of a GI Joe kid. It always bothered me that, as toys, Transformers were clearly compromised in both states. Folded up, they weren’t good cars / trucks / fighter jets. They had obvious seams and folds. In the cartoons — and the subsequent live action films decades later — the Transformers’ disguised states are seamless. In real life with the actual toys, the disguised states were about as convincing as a pair of Groucho glasses. A regular toy car looked like a real car, and stayed together no matter how hard you played with it. A Transformer car never quite looked like a real car and would come apart when played with. Unfolded, they looked like robots, yes, but they had obvious compromises. And it was kind of a pain folding them back into vehicles. My recollection is that we played with them a lot more as unfolded robots than as folded vehicles.

And that’s what they were. They weren’t vehicles that pretended to be robots. They were robots in disguise. The Duo isn’t really a phone. It’s a tablet in disguise. And in the same way that a true toy car was a better toy car than a folded-up Transformer-as-car could ever be, the Duo-as-phone is just not as good a phone as any regular iPhone. Honestly it’s not even close.

Consider if you could snap the Duo in half, leaving the smaller outer display as a standalone iPhone. Would anyone want an iPhone this shape and size? I think the answer is that zero people would want this. The iPhone Mini, back in 2020 and 2021 with the iPhone 12/13 generations, proved not to be popular enough for Apple to keep around. The iPhone Minis were a way better shape than the outer Duo. There’s a reason why the iPhone Air is not shaped like half a Duo — because the Duo shape stinks as an iPhone. And that’s only considering the hypothetical of a thin lightweight Duo snapped in half. In real life, with the actual Duo, when you use it folded up the device is twice as thick and twice as heavy. These Transformer watches were a fun way to smuggle a toy robot into school, but they were crummy watches. The iPhone Duo is a fun way to fit an entire iPad Mini–sized tablet into your pocket, but it’s a cumbersome phone.

It does not go into or out of my jeans pocket smoothly. Folded up it never stops feeling heavy. It is heavy, compared to other iPhones:

iPhone	Weight
Duo	254g
18 Pro Max	249g
18 Pro	211g
17	177g
Air	165g

It’s technically only negligibly heavier than an 18 Pro Max, but because it has so much less surface area, it feels far more dense. If it did not unfold, no one would buy this.

But, of course, it does unfold. That’s the entire point. Unfolded, it not only no longer feels heavy, it feels featherweight light. It’s uncanny. An open iPhone Duo has a 7.6-inch display and the physical dimensions are 4.6⁠ ⁠×⁠ ⁠6.5 inches. An A17 Pro iPad Mini (the current model, but supposedly not for long) has an 8.3-inch display, measures 5.3⁠ ⁠×⁠ ⁠7.7 inches, and weighs 297g (that’s the cellular model’s weight, which is only fair). The iPad Mini has a slightly bigger screen but it’s heavier. In hand, I prefer the unfolded Duo over the iPad Mini as a tablet, in every single regard other than hardware button placement. (More on that below.)

You simply cannot have your cake and eat it too. The Duo allows you to take what is, in several ways, the best tablet Apple has ever made — and thus, the best tablet any company has ever made — fold it in half, and put it in your pocket to carry everywhere. While folded in half, you can use it as an entirely functional iPhone, but it’s by far the worst iPhone experience ever — frustrating, ungainly, and uncomfortable.

Using the Duo Closed, With the Outer Display

Ever since it was unveiled there’s been idle speculation that, while folded, the Duo’s design is biased against left-handed users. First, because the Touch ID side button is on the right. Second, because the Duo variant of iOS moves things like application toolbars and the home screen Dock to the right.

I am right-handed, but I’m a little bit on the ambidextrous spectrum. For example, I switched to using my mouse with my left hand around 1995, when I developed RSI in my right wrist, and I’ve used my mouse left-handed ever since. (But I use a MacBook trackpad with my right thumb.) I can shoot a basketball from close range with my left hand. So going into my Duo review, I thought I’d try to use my Duo as a pretend lefty. Turns out I didn’t have to pretend. I never realized this, but I naturally use my iPhone left-handed quite a bit throughout the day. For example, while brushing my teeth. I keep my iPhone in my right front pants pocket, but I often pick it up off my desk or kitchen counter and use it left-handed.

The Duo is not comfortable left-handed. The problem isn’t the Touch ID side button — I fixed that by registering my left index and middle fingers with the Touch ID sensor. The problem isn’t right-side bias for toolbars and the Dock in iOS Duo.¹ That’s not great for left-handed use, but the truth is there’s a reachability problem no matter which single hand you try holding the Duo in. It’s better to hold it in your right hand than left, reachability-wise, but fundamentally it’s so wide that it’s a two-handed device even when being used folded.

No, the problem with holding the Duo in your left hand alone is that the bottom left corner of its D-shaped frame digs into your palm. When you hold it in your right hand, it’s a nice round corner in the meat of your thumb’s base. In your left, it’s a crisp sharp corner, and it doesn’t feel good.

When using the small outer display, everything on screen feels cramped. I don’t even like the home screen. Moving the Dock to the right side breaks 19 years of spatial memory for me.² I keep reaching for Messages, Notes, and Safari down at the bottom of my screen, when now they’re over on the right. And they look weird too, because they’re smaller icons than the others on the home screen. Ostensibly the Dock is for your four most-used apps, but now they’re the smallest icons on your home screen? What sense does that make?

It’s such a little thing (no pun intended, I swear), but it exemplifies how many compromises Apple had to make for this small squat display.

Next, consider this screenshot from NetNewsWire:

Daring Fireball

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