Several new features stand out in iOS 11, the coming update to Apple's mobile operating system that became available in public beta yesterday. They include a new keyboard mode for easier one-handed typing, a "Do Not Disturb" feature for driving, and the option to ask digital assistant Siri questions by typing rather than speaking.

Set for general release in September, iOS 11 will be the "biggest software release ever for iPad," according to Apple. For now, however, the developer preview and public beta are not necessarily "ready for prime time," so users should expect bugs and avoid downloading the OS onto their primary work or personal devices.

Early reviews of the iOS 11 beta are calling the update "massive," great," and "ambitious," and note the changes are particularly noticeable on the iPad. TechCrunch, for instance, said the operating system "feels like a completely new beast on the iPad."

Half-Keyboard & Handwritten Email Options

Unveiled earlier this month at Apple's Worldwide Developer Conference, iOS 11 will bring "hundreds of updates" to Apple devices. Changes include new multitasking capabilities, support for quick money transfers to personal contacts via Apple Pay, a redesigned App Store, and more customization options for the Control Center and Dock for accessing frequently used apps.

For users on the road, the "Do Not Disturb" feature automatically silences notifications to keep iPhones dark and reduce interruptions. Users can also have automatic replies sent to their favorite contacts letting them know they're driving and will respond later.

The updated keyboard, meanwhile, gives users the option of using Apple's standard QuickType keyboard or shifting a half-screen keyboard to the right or the left of their iPhone screens. The narrower typing interface is designed to make it easier for users to type one-handed without having to reach across the entire screen to reach different characters. Users will also be able to handwrite messages and insert them into Apple Mail to send as drawings.

In addition to being accessible via typing as well as by voice command, Apple's intelligent digital assistant Siri will also feature new capabilities such as "more natural and expresive" voices, and translating abilities from English into French, German, Italian, Mandarin, and Spanish.

Also Coming: Improved VR, New iPad Features

For developers, iOS 11 will bring support for creating new iPhone and iPad apps for intelligent automation, smart homes, music integration, and virtual reality. The new ARKit framework, for example, will enable applications with greater device motion awareness, surface recognition, and image rendering, allowing developers to "build detailed and compelling virtual content on top of real-world scenes for interactive gaming, immersive shopping experiences, industrial design, and more."

iPads will gain new capabilities through new support for dragging and dropping text, images, and files from app to app. iPad users will also see enhancements for multitasking, as well as a revised Files app designed to make it easier to find, open, and share files.

When it's ready for final release later this year, iOS 11 will be available on all models of the iPad Air and iPad Pro, as well as the iPhone 5s and up, 5th-generation iPad, 6th-generation iPod touch and iPad mini 2 and up.

While the operating system is normally updated immediately prior to the launch of new iPhones, this year's phone releases might be delayed until October or November, according to various sources. 2017 marks the 10th anniversary of the release of the first iPhone, and Apple reportedly plans to hit the market with three new devices this fall: an iPhone 7s, an iPhone 7s Plus, and -- rather than the iPhone 8 -- the "iPhone Edition."