Adobe has updated their Adobe Reader app for Windows Phone 8 to version 10.3, adding support for annotating and commenting on PDF files. When viewing a PDF file it is now possible to highlight, underline and strikethrough text (annotations) and add comments as a sticky note. These edits can be saved to the PDF file and will be viewable in other Adobe Reader clients.

Also new is support for storing, sharing, and accessing documents via the Acrobat.com cloud service. Once logged into your Acrobat.com account you can access PDF files stored on the cloud service. PDF files stored on your phone can also be uploaded to the service, making it easier to share files with other people. The service also allows you to synchronize PDF files across multiple device, with reading position, comments and annotations, automatically saved to the cloud.

A number of Adobe Acrobat related services are available through an Acrobat.com subscription. The basic membership level is free and comes with 5GB of personal file storage, which should be more than enough for most users to get started. Additional storage space and services (e.g. online conversion and export tools) are available as part of a number of premium subscription packages.

The latest update to Adobe Reader puts the app ahead of other third party PDF applications, including Microsoft's own PDF Reader app, in terms of features and functionality. The additions to app make it possible for common PDF workflow tasks to be carried out on a Windows Phone device, further burnishing the platforms credentials as an enterprise ready product. 

Adobe first released a Windows Phone 8 optimised version of their Adobe Reader app in June of this year.

Windows Phone Store description:

Adobe Reader is the free, trusted leader for reliably viewing and interacting with PDF documents across platforms and devices. Install the free Adobe Reader mobile app to work with PDF documents on your Windows Phone devices. Easily access a wide variety of PDF types, including password-protected documents. 

Annotate and comment on PDF documents
• Provide feedback using the highlight, strikethrough, and underline tools
• Add comments anywhere in your PDF with sticky notes

Store and access documents in the cloud with Acrobat.com 
• Share files with anyone using Acrobat.com file sharing
• Share files across all of your desktop and mobile devices with Acrobat.com
• Automatically save changes back to the cloud
• Synchronize where you are reading across multiple devices via Acrobat.com

Adobe Reader is a free download for Windows Phone 8 from the Windows Phone Store. The Windows Phone 7.5 version remains available for older devices.