iPhone Duo pre-orders open this week — but there are still 7 things we don't know

(Image credit: Tom's Guide) Pre-orders for the iPhone Duo open officially kick off this Wednesday, giving eager foldable enthusiasts the chance to secure their device ahead of the October 23 release date. While many of you will already be taking steps to get that pre-order on day one, and avoid lengthy delays, we should all be aware there are things we still don't know about Apple's first foldable phone.I'm not talking about major surprises like hidden features or hardware specs, since Apple has been very open so far. I mean the kind of things you can only learn from actually using a phone for extended periods of time. And some of them might be the difference between eagerly ordering an iPhone Duo, and deciding that you might be better off waiting for the second or third iteration of the phone.Here are 7 things we still don't really know about the iPhone Duo.What's the battery life really like? (Image credit: Tom's Guide)Phone companies love to brag about the longevity of their batteries, and how long a phone will last on a single charge. Apple is no exception to this.The iPhone Duo rated for 44 hours of video playback from the external display and 31 hours using the larger folding screen. But how will that translate into real-world usage? It's unclear, and since we haven't been able to test the iPhone Duo's battery for ourselves yet, we can't say how the phone compares to other iPhones or foldables.Apple says the iPhone 18 Pro can handle up to 36 hours of video playback, while the Pro Max can last 45. On the Tom's Guide Battery Test, which consists of 5G web surfing, the iPhone 18 Pro endured for 16 hours and 17 minutes, and the Pro Max lasted 18 hours 27 minutes.That gives us a rough idea of how the iPhone Duo should perform in our battery test. More so when you consider that much of the internal hardware is the same, including the energy-efficient A20 Pro and C2 modem. So here's hoping the Duo does offer similar results, though we obviously won't know for sure until we get to test one properly.Sign up to the Tom's iGuide weekly newsletter with coverage on everything from product launches to software updates, this is your go-to source for the latest updates on all the best Apple content.How good is the screen really? (Image credit: Tom's Guide)A lot of emphasis has been put on the iPhone Duo's foldable screen, and not just because it folds. Apple has opted for a matte "nano-texture" display, rather than the glossy glass panels you'll find on most premium phones.While we're starting to come round to the idea of this new kind of display, there's still the question of how well the screen will actually perform in different conditions. I'm especially curious to see how the phone handles bright environments, especially compared to the anti-reflective coating Samsung has applied to the Galaxy Z Fold 8 and Z Fold 8 Ultra.There's also the lingering question of how the nano-texture coating will affect colors and image quality.Finally, Apple has made a very big deal about the fact the Duo has no visible display crease, but will it stay that way forever? As we've seen with other foldables, the display crease has a habit of appearing over time, even if it wasn't there at launch. So it'll be interesting to see what Duo screens look like three to six months from now.What's accessory support going to be like? (Image credit: Apple)We know that the iPhone Duo supports MagSafe, but the phone's unique shape means that a lot of existing MagSafe accessories aren't going to fit. We've already seen examples of that pop up online, including images that suggest the phone is too short to attach a MagSafe card wallet neatly.You can't change the size of a credit card, and it has me worried that other MagSafe accessories are going to be affected in similar ways. Chargers should be fine, but things like batteries and stands may look a little awkward.The shape means that other wraparound accessories, like USB-C game controllers, are going to have a hard time connecting to the phone. While this is a problem all foldables have to face, it means anyone with an existing controller may have to invest in a wireless option.How good are the cameras? (Image credit: Tom's Guide)Apple has earned a lot of goodwill where cameras are concerned, having consistently offered some of the best camera phones for years. But like the iPhone Air before it, we have some worries that the iPhone Duo may not be able to live up to the quality currently afforded by iPhone 18 Pro and Pro Max.Most concerning is the fact that there's no telephoto lens, and Apple is opting for the digital-only "optical quality" feature to simulate zoomed in shots instead.The camera hardware looks pretty similar on paper, even if the foldable lacks the new variable aperture technology, and this suggests that iPhone Duo will do a good job with the lenses it has. Modern smartphone photography is as much about the software as it is the hardware, after all. We saw that with the iPhone Air, which took great pictures despite the fact it only has a single lens.But, as we saw with the Galaxy Z Fold 8, the loss of that third lens can have an impact, and we won't know what the situation is until after the iPhone Duo is released.Is it as durable as Apple says? (Image credit: Tom's Guide)Durability has been the foldable phone's weakness for a long time, especially when some of them still don't bother to seal the chassis to protect against dust. Apple seems to have done a bunch of things to ensure that its own phone doesn't fall into those pitfalls, but that doesn't necessarily mean everything will work out ok.After all, we did experience the scratchgate problems with iPhone 17 Pro and Pro Max. The switch from titanium to anodized aluminum and the raised camera bar, meant that the phone was more prone to scratches and scuffs compared to older models.The iPhone Duo will benefit from the fact it's made from Grade 5 titanium, the same as iPhone 15 Pro and iPhone 16 Pro, as well as the impressive strength of Ceramic Shield 2 on the front display. But that doesn't necessarily mean things can't go wrong somewhere, and the durability of the foldable screen is a notable unknown.This is something we can't really learn about until reviewers get their hands on the iPhone Duo.Third-party app optimization (Image credit: Tom's Guide)The software experience is one of the iPhone Duo's main selling points, and we know that Apple has done a lot to ensure that apps are optimized for the new screen sizes.But just because Apple and a handful of third-party developers have been working to get their apps looking good on the dual displays doesn't mean all apps will look that good. Optimizing apps does involve work from the developer, and it's something that a lot of them willfully ignore.You only have to look at all the Android apps that are just blown-up versions of phone apps to see this in action. Here's hoping that there will be dozens if not hundreds of apps optimized for the iPhone Duo on day one.Long term comfort (Image credit: Tom's Guide / Jeff Parsons)One of the things we noticed during our iPhone Duo hands-on is that this is definitely not the thinnest or lightest foldable you can buy. In fact, with a weight of 8.9 ounces, it's the heaviest iPhone Apple has ever made. Combined with a form factor people aren't used to, it makes me wonder what kind of impact there will be on long-term comfort.I'll admit, this is not the biggest issue in the world. The Galaxy Z Fold 8 already proved that the wider form factor is more comfortable than the larger screens of the Galaxy Z Fold 8 Ultra. But the Fold 8 is nearly 2 ounces lighter than the Duo.Until we are able to spend an extended amount of time with the iPhone Duo, we won't know for sure whether the design and weight start taking their toll after a few hours of extended use. Stay tuned for our full iPhone Duo review and test results. Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds. More from Tom's GuideSpaceX just announced plans to make Starlink a 'major' US mobile carrieriPhone Duo — I ranked the 9 biggest reasons to buy Apple’s first foldableYour iPhone secretly locks down after 72 hours — this forensic tool may have found a way around it Tom is the Tom's Guide's UK Phones Editor, tackling the latest smartphone news and vocally expressing his opinions about upcoming features or changes. It's long way from his days as editor of Gizmodo UK, when pretty much everything was on the table. He’s usually found trying to squeeze another giant Lego set onto the shelf, draining very large cups of coffee, or complaining about how terrible his Smart TV is.