Microsoft has released a free upgrade to Office Mobile after the release of the main product

Go to https://marketplace.windowsphone.com/details.aspx?appId=3c5f7fc0-313e-4518-8786-e13ca4873815&retURL=/categories.aspx?categoryId=51523&wa=wsignin1.0 for the upgrade

As part of this release, you will find SharePoint Workspace Mobile which will provide the same functionalities than the client version.