When we reviewed iOS 6 a year ago, we called it a "spit-and-polish" release and we stand by that assessment today. Between the new Notification Center, iCloud, and iMessage, iOS 5 felt like a big, substantial release in ways that its immediate successor did not. A lack of impressive new features (the useful-but-minor Do Not Disturb, the niche Passbook, the busted Maps) and a visual design that was just past its fifth birthday both contributed to a feeling of inertia in iOS 6. There was a sense it was time for a change.

Boy, did we get one. iOS 6 had barely been out for a month before Scott Forstall, the exec who led the iOS team for as long as there had been an iOS team, left (or was ejected from) the company. Craig Federighi and Jony Ive, the Apple senior vice presidents in charge of OS X and hardware design, respectively, stepped in to fill his shoes. Today we're looking at the result of that switch.

In one sense, iOS 7 changes nearly everything about iOS. A couple of wallpapers have made the jump, but otherwise you'd be hard-pressed to find anything in iOS 7 that looks quite like it did in iOS 6. In another sense, iOS 7 is the latest in a string of incremental updates. It adds a few new features and changes some existing ones, but this doesn't radically alter the way that you use the OS from day to day. Our in-depth review explores every nook and cranny of the new operating system to show you which additions actually improve iOS, and which ones are only skin deep.

Supported devices and feature fragmentation

Before we dig in, let’s talk about installation. For the purposes of this review, we’ll be omitting any iOS features unique to the iPhone 5C and 5S (don’t worry—they’ll each be getting their own reviews soon) and focusing entirely on the devices that are in your hands right now. The full list of devices that support iOS 7 reads as follows:

The iPhone 4, 4S, 5, 5C, and 5S

The iPad 2, third- and fourth-generation iPads, and the iPad mini

The fifth-generation iPod touch

Two devices that supported iOS 6 have been dropped by iOS 7: the iPhone 3GS and the fourth-generation iPod touch. Both were dropped for good reason. The iPhone 3GS was the last of the small-screened iOS devices to lack a Retina display, and both devices are stuck with 256MB of RAM where the others have at least 512MB.

The length of the iOS device support cycle remains about the same as it has been for the last couple of years. If you buy an iOS device when it’s brand new, you can (with some notable exceptions) expect three to four years of software support, even if your device won’t get every new feature promised by every new software update. While it isn’t the concern that it is for Android devices, iOS has a little fragmentation of its own. As the iOS family gets larger, that matrix of unsupported features gets more complicated. Apple provides a full breakdown that we’ll repost here with some light editing and additions:

Panorama shooting is available on iPhone 4S or later and iPod touch (5th generation). Square and video formats and swipe to capture are available on iPhone 4 or later, iPad (3rd generation or later), iPad mini, and iPod touch (5th generation).

Filters in-Camera are available on iPhone 4S or later and iPod touch (5th generation)—Apple lists that only the iPhone 5 and newer should be able to use this feature, but as of the GM build, our iPhone 4S supports it too. Filters in Photos are available on iPhone 4 or later, iPad (3rd generation or later), iPad mini, and iPod touch (5th generation).

AirDrop is available on iPhone 5 or later, iPad (4th generation), iPad mini, and iPod touch (5th generation) and it requires an iCloud account.

Siri is available on iPhone 4S or later, iPad with Retina display, iPad mini, and iPod touch (5th generation), and it requires Internet access.

Finally, the iPhone 4 and its older A4 chip do not support the following features: the 3D Flyover feature and turn-by-turn navigation in Maps; AirPlay mirroring; translucency effects throughout the OS; live wallpapers; and some visual effects including the parallax effect on the Home screen.

Ever since iOS 4.0 brought the iPhone 3G to its knees, performance on older hardware has been a concern among upgraders. We’ll talk generally about performance and battery life later on in the review, but I’ll be revisiting the iPhone 4 in particular in a separate article soon. Ars Associate Writer Casey Johnston will also be spending time with the software on an older iPad 2 and reporting back on her experiences later this week.

Installation and setup

The iOS 7 update can be installed either via iTunes or by the built-in software updater in iOS 6. You’ll need an Internet connection of some kind to download the update and to activate newly purchased or registered devices. iOS 7 will leave your device with just a tiny bit less usable space than it had under iOS 6—just how much less varies from device to device, though the iPads typically take a bigger hit than the iPhones do. If you’re already squeezed for space, iOS 7 will squeeze just a tiny bit harder.

Device Space available (iOS 6) Space available (iOS 7) 16GB iPhone 4 (AT&T) 13.3GB 13.2GB 32GB iPhone 4S (AT&T) 27.8GB 27.5GB 32GB iPhone 5 (VZW) 27.5GB 27.3GB 32GB iPod touch 5 27.8GB 27.3GB 16GB iPad mini (Wi-Fi) 13.4GB 13.1GB 32GB iPad 4 (Wi-Fi) 27.4GB 26.7GB

The setup screens you’ll see on an iPhone 5 are located in the image gallery below for your convenience (the iPad screens are identical, just larger), but if you’ve set up an iOS device before, the design will be the only thing new about this process. One notable change is that devices now ask you to create a four-digit passcode during setup. This is skippable, but we’re glad to see Apple encouraging its users to protect their devices even at this basic level. Apple’s Phil Schiller mentioned during the company’s September 10 keynote that about half of iOS users didn’t set up a passcode at all, and Apple would apparently like that to change, even on devices without a fancy fingerprint scanner.