OneNote is fine if you use OneNote on a PC, Mac, iOS device, or Android device, as it syncs across all devices attached to your Microsoft account. But iOS's Notes app is more flexible because it can sync not only across iCloud devices but across IMAP accounts, too. OneNote does let you apply character and list formatting to your notes, unlike Notes. (Android has no stock note-taking app.)
Office in Windows Phone 8 has been improved to support basic formatting for Word files you create, but that's it -- there's no support for paragraph formatting, much less tables, revisions tracking, or comments. Excel offers more capabilities for files you create in it, including sorting, chart creating, and formula editing. For PowerPoint, all you can do is add or edit notes to presentations created elsewhere. When I tried to open Word or Excel files created on a PC, Office told me consistently there were features in those files it could not handle and, thus, could not edit the files. You might have some Word or Excel documents that Office for Windows Phone 8 can open, but it's not likely.
Also, from within Office, you can access only files from Microsoft's own SkyDrive and Office 365 cloud services, as well as from SharePoint servers and email attachments. You can open Office from other apps, such as the Box cloud storage service, but you have to start in those apps to see the files. Quickoffice for Android and iOS aren't biased in this way, and even Apple's iWork apps for iOS can directly open files from outside Apple's proprietary iCloud and iTunes from third-party services that support the WebDAV protocol.
Neither iOS nor Android comes with a free office productivity app, but the iWork suite (the $10 Pages, $10 Keynote, and $10 Numbers) for iOS and $20 Quickoffice Pro for iOS and Android are very capable editing apps worth their small cost. Unfortunately, there are no equivalent apps as yet for Windows Phone 8. Because of Office's deficiencies, you can't depend on it to do basic edits or fixes in a pinch as you can on an iPhone or Android smartphone. Basically, Office for Windows Phone 8 is useless.