Can you do this : Edit documents anywhere without corrupting them?

Seems pretty fundamental, right?  If you are going to provide document editing capability across mobile, workstation, and browser devices a basic expectation would be don't compromise or corrupt the original. Unfortunately with many solutions this is simply not the case, but with Office365 you can edit with confidence on whichever platform you choose.

Have a look at what I mean in Word web app vs Google Docs (this isn't canned, its the same document rendered on your browser by each solution realtime)

https://sharepoint.microsoft.com/businessproductivity/en-us/Why-Microsoft/compare-demo/Pages/google-documents-vs-word-web-app.aspx

and again with Excel web app vs Google Spreadsheets.  This one is nasty

https://sharepoint.microsoft.com/businessproductivity/en-us/Why-Microsoft/compare-demo/Pages/google-spreadsheets-vs-excel-web-app.aspx

I know I'm biased :)  You decide which one you'd want to use.