The most striking changes to Microsoft's new operating system are evident as soon as you first switch on a Windows 8. The process is surprisingly fast for Windows: gone are the days of staring at an ugly splash screen or waiting for Windows to apply computer settings before you can log in and progress with your day. In fact, the boot process is so fast on new hardware that you barely see the redesigned Windows logo that greets you ahead of an entirely new OS.

Microsoft's Windows 8 user interface, originally referred to as Metro-inspired - a nod to the company's internal design language - is as stunning as it is surprising. Taking visual elements from Microsoft's Windows Phone design, the Start screen is the first thing you'll experience when you log in. There's no Start button, no desktop - just rows of colorful, constantly changing tiles. The interface can be customized with backgrounds and colors for those wishing to dig deeper. If you've configured a Microsoft account that uses Outlook.com or Hotmail, then you'll notice that email, calendar, and contacts will automatically appear. If your Microsoft account is linked to Facebook, your Facebook contacts will also appear in the People app and its associated tile. Immediately, this unfamiliar interface already looks like it's customized to you, with your friends' faces ticking away on the People Live Tile and photos you've stored on SkyDrive or Facebook showing up automatically on the associated Live Tile.

The Search charm is context-aware, meaning you can use it to search while you’re in an app or to trigger searches across files and settings. A Share charm acts as a way to pass information from one app to another — sharing a URL to the Mail app for example, but it formats an email with images and a subject rather than just copying and pasting the URL. Devices is fairly self explanatory, offering a basic look at devices you can send content to — such as a printer or a second screen. The Settings charm is one of the more confusing aspects to Windows 8. Like all other Charms, it’s context-aware, meaning that you’ll use it to access settings in every app.

The biggest change in Windows 8 facilitates a new breed of apps. Known previously as Metro style apps, the new Windows 8-style apps are not compatible with previous versions of Windows and are available in a new Windows Store that Microsoft is curating. They are designed to be touch-friendly and full-screen, and they represent Microsoft’s riskiest bet in Windows 8. For Windows 8 to truly succeed on tablets, laptops, and desktop PCs, it needs developers to create functional and good-looking apps that work across a variety of display and input types.

The Music and Video apps mark a switch in direction for Microsoft. Built by the company’s Xbox team, they provide access to the entertainment aspects of Windows 8. Music includes free, ad-supported Xbox Music streaming — available in 15 markets initially. Microsoft has a catalog of 30 million tracks worldwide, and offers a subscription service without advertising for $9.99 per month which will also work across Xbox and Windows Phone 8. The free ad-supported streaming is only available on Windows 8.

One last radical change for Windows 8 is the changes to the lock screen. A colorful design with mountains and Seattle’s space needle will greet you every time you start a Windows 8 (you can customize the picture as well). Microsoft has opted to provide time, date, calendar entries, network status, and battery levels as default, but you can display up to seven lock screen apps that will provide quick status and notifications when a screen is locked. This is particularly useful if you want to glance at a mobile device to see how many calendar appointments you have during the day or the amount of emails in your inbox.