1. The Cloud. Having and data from virtually any Web-connected device, anywhere, and any time has its advantages. Google Docs provides a relatively consistent experience across different devices from Windows and Mac PCs, to Android smartphones and tablets, and iPhone--although Google Docs from the .
2. Collections. It took a little getting used to, but once I familiarized myself, the idea of rather than the files and folders I am used to on my PC made great sense. A file can only exist in one folder (although you could place copies or shortcuts in other folders), but the Google Docs collections let you organize a single file in a variety of ways. For example, a spreadsheet calculating expenses for a golf league can be tagged as a "spreadsheet", "expenses", and "golf" collections so that you can find and work with it in whatever way makes sense to you.
3. Discussions. I do a lot of writing, and after writing comes editing. I appreciate the comments in Microsoft Word--as opposed to just adding comments and feedback inline with the content, but the takes commenting to the next level. I am particularly fond of being able to mark a discussion as "resolved" so it doesn't continue to clutter up the document, but for future reference rather than deleted.
4. Collaboration. Aside from the fact that Google Docs is a Web-based productivity platform, real-time collaboration is probably the most . Whether you are working on a document, spreadsheet, or presentation, the file can be shared with others, and all parties can work with the file at the same time--simultaneously updating it and making changes while chatting with one another on the side. Combining real-time collaboration with Google Docs Drawing app is great for whiteboard collaboration sessions.
5. Power Tools. I was impressed by the tools to dynamically pull in Google search results using things like from within a spreadsheet cell. I can think of a variety of valuable uses for tools like these that let you pull in content and keep it updated as teh information changes.