[13] The Control Center is now customizable, and allows more settings to be shown,[12][14] including cellular service, Low Power Mode, and a shortcut to the Notes app.

[15] The Siri intelligent personal assistant has a more human voice and supports language translation, with English, Chinese, French, German, Italian and Spanish available at launch.

[3] A new "Do Not Disturb While Driving" mode lets users block unnecessary notifications as long as their iPhone is connected to a vehicle through Bluetooth.

The application dock gets an overhaul, bringing it closer to the design seen on macOS, and is accessible from any screen, letting users more easily open apps in split-screen view.

[33] Each letter on the iPad keyboard features an alternative background number or symbol, accessible by pulling down on the respective key and releasing.

[4][35] iOS 11 introduces optical image stabilization, flash photography and high dynamic range for portrait photos.

[17] Once a QR code is positioned in front of the camera, a notification is created offering suggestions for actions based on the scanned content.

Twitter users have so far discovered that joining Wi-Fi networks and adding someone to the contacts list are supported through QR codes.

[55][56] Many of Apple's pre-installed applications, including Notes, Contacts, Reminders,[57] Maps, and App Store, have redesigned home screen icons.

[58] An "Emergency SOS" feature was added that disables Touch ID after pressing the Sleep/Wake button five times in quick succession.

[17][80] The Notes app has a built-in document scanner[30] using the device's camera, and the feature removes artifacts such as glare and perspective.

The app supports organization through structured sub-folders and various file-based options,[30][31][85] and it also includes a built-in player for FLAC audio files.

[90] A new "ARKit" application programming interface (API) lets third-party developers build augmented reality apps, taking advantage of a device's camera, CPU, GPU, and motion sensors.

[103] Apple's software engineering chief Craig Federighi wrote in reply to an email that the company had to "temporarily drop support" due to a "technical constraint," pledging to bring it back in a future update to iOS 11.

[106] In iOS 11.2, the toggle switch for Wi-Fi and Bluetooth were unexpectedly changed to not completely turning off those two things but temporarily until the next day.

Writing that "Multitasking on the iPad is a near-revelatory experience", he enjoyed the application dock and the ability to place up to three apps on the screen at once with more freedom on placement.

Bohn conceded that "It's not as intuitive nor as simple nor [sic] as easy to manipulate as a traditional windowing system like you'll get on a Mac, PC, or Chromebook", but still praised it for being "radically more powerful than what has ever been available on an iPad before".

Finally, Bohn praised Siri for improvements to the voice, highlighted augmented reality allowing for "incredible games", and reiterated an earlier sentiment that iOS 11 is "the most ambitious software update from Apple in a very, very long time".

He also praised the Control Center design, calling it "a great upgrade", though also highlighting the inability to easily switch Wi-Fi networks.

Snell also praised improvements to the iPad experience, including multitasking and drag-and-drop across apps, the latter of which he stated "actually surpasses my expectations" due to ease of use.

Finally, Hardawar also enjoyed new functionality on iPad, calling multitasking, the application dock and drag-and-drop "dramatic changes," and highlighting the "particularly useful" experience of dragging Internet content directly from the web into the new Files app.

"[117] In November 2017, Gizmodo's Adam Clark Estes wrote extensively on software bugs and product imperfections experienced while using iOS 11.

He concluded by theorizing on technological development, writing: "However, I am trying to understand exactly how my life with computers veered so dramatically from the days of Windows 95 when nothing worked right, to the golden age of the iPhone 4 when everything seemed perfect, to now when just a handful of iOS bugs make me feel like the world is falling apart.

"[118] Shortly after iOS 11 was released, Vice's Motherboard discovered new behaviors by the Wi-Fi and Bluetooth toggles in the Control Center.

The Foundation recommended that Apple fix the "loophole in connectivity", writing that "It's simply a question of communicating better to users, and giving them control and clarity when they want their settings off - not "off-ish"".

[127] It has been recommended by technology experts that users not upgrade their software until the release of a version subsequent to 11.3.1 unless specifically plagued by the 'third party display issue'.

[127] In October 2017, users reported on Reddit that quickly typing in an equation in the built-in iOS Calculator app gives incorrect answers, most notably making the query "1+2+3" result in "24" rather than "6".

With a large amount of bug reports filed, Apple employee Chris Espinosa indicated on Twitter that the company was aware of the issue.

[123] In November 2017, users reported a bug in the default iOS keyboard, in which pressing "I" resulted in the system rendering the text as "!"

MacRumors wrote that the issue "looks like it's limited to devices running iOS 11.1.2", with users on the 11.2 beta release not affected.