The formatting is often not retained when Office documents are opened inside Google Docs Viewer
Google Docs Viewer is a useful service that helps you preview Microsoft Office files in the browser itself. The online tool can come handy when you don’t have the Office suite installed on your computer or when you would like to quickly preview the content of an online document without having to download it locally.
Office Web Apps, Microsoft’s answer to Google Docs, too offer a similar online document viewer that is superior to Google’s tool as it retains the formatting while rendering the document in the browser.
For instance, here’s a standard PowerPoint presentation (PPT) in Google Docs Viewerand the same file rendered inside Office Viewer. Next, compare a slightly-complex Word document (docx) inside Google Viewer and Office Viewer. The latter retains all the styling and even the fonts look sharp there.

How to Use Office Web Apps Viewer

If you are to open an online document/spreadsheet/presentation inside the Office viewer, all you need to do is append the URL (web address) of that file to “view.officeapps.live.com” as shown in the following examples:
http://view.officeapps.live.com/op/view.aspx?src=http://img.labnol.org/di/Word.docx

http://view.officeapps.live.com/op/view.aspx?src=http://img.labnol.org/di/PowerPoint.ppt
In addition to previewing Office files, the same Office Web Apps Viewer tool can also be used for embedding Microsoft Office documents into your website or blog. The embed code would be something like this:
<iframe src='https://view.officeapps.live.com/op/embed.aspx?src=http://img.labnol.org/di/PowerPoint.ppt' width='500px' height='350px' frameborder='0'></iframe>
You need to replace the actual URL of the document and may also adjust the height and width attributes of the IFRAME tag.
While Office Web Apps viewer is definitely a better option that Google Docs Viewer, a limitation is that it only works with Office Files, Google Docs Viewer can also handle PDFs, Photoshop files and even AutoCAD drawings.