If you are on a certain data plan on your mobile provider, and don't want to exceed it, you can set data usage warning and a limit which can help you save some of your money.
Not only that you can share files — like documents, images, and PDFs — without having to email them as attachments. You can share the whole folder containing the documents.
You can upload and import any MS Word document file to Google docs/drive as you can download and export a Google docs document to you computer and open it with MS Word.