Office is one of the key selling points of Windows Phone. Document viewing and editing is absolutely free and integrated into the OS. SkyDrive integration is available as well. Docs are automatically synced between the phone and your computer via SkyDrive.
The Places tab lets you browse Office docs stored on the phone, in SkyDrive, email or in Office 365 (a paid service that includes Office web apps).
The Office hub breaks down into three sections - Documents, Places and Notes.
Let's look at the two most important apps - Word and Excel. They share the Documents panel, which lists all available documents of the relevant types (in order of last used). Both viewing and editing is supported.
The Excel section of the Office hub has the Auto-sum function and you can tap and drag to select multiple cells.
Editing is pretty straightforward even on a mobile device. You type in the text and you can use the Format key to change the formatting of the selected text. You can also insert comments.
Formatting options include the standard bold, italic and underline, as well as text size, highlighting and font color. For highlighting and font colors you have only three colors to choose from, which is a little limiting but should be enough for most cases.
PowerPoint files will thrive in the Documents section too - but they are for viewing only, you can't edit them or create new ones.
Collaboration for both Word and Excel files is enabled with SharePoint. It allows syncing, sharing and web publishing but you'd need to use the right SharePoint server. You can attach those files to emails, though you need to do that from the Office hub. You can't do it from the email editor, which caused a little confusion at first.
OneNote is Microsoft's collaborative note taking tool. It has great (and easy to use) support for lists of multiple levels, you can add photos and voice memos and you can email notes too. OneNotes can be synced with your SkyDrive or Windows Live account so that they are accessible everywhere. Pin-to-homescreen is available too and so is the To-Do feature that turns the selected line into a to-do item that can be checked off.
The apps support pinch zooming and work very well for viewing even complex documents. But Microsoft's fondness of simplicity may have over-simplified the editors.
The Calendar can view sub-calendars for each account you have and can color-code to make them easier to tell apart. You can also disable sub-calendars if they're getting in the way.
The calendar offers day and agenda views too for more detailed hour-by-hour browsing of your appointments.
To-dos can be created too. Those can only be synced with Live accounts, and not a Gmail account for example. Each to-do can have a priority reminder, due date and notes. Later, to-do's can be sorted by priority.
The WP calculator is nothing extravagant - it has the simple portrait view of basically all calculators on the planet, while turning it over to landscape reveals the more complex scientific mode.
The alarm app is very simple to use. You get the alarm time with an on/off switch to the right. Each alarm can have its own name, sound and repeat.