Collaborate in Excel is not trait forward and confusing for newbies
You really must create a better and more guided approach to collaborating across Office applications, in particular Excel. For newbies or users of Google Apps it's very confusing and tricky to collaborate without getting a locked or read-only file. Especially, when each collaborator has different Office 365 Accounts for different companies. Another example, if a collaborator works for Microsoft, another is a student at WSU, and a third has a personal office subsription, there just isn't an intuitive or well through through integration to get this to work together. If it doesn't work there is no indication why or guided approach to help the user solve the problem. Absolutely, horrific experience preventing Office adoption from other competing products.