Office 365 is one of my most used applications. I love the way that I can leverage the Cloud capabilities of my Office applications to access from anywhere. I have access from my phone, tablet, laptop, desktop, etc., and it is always easy. Outlook is nice when I do not have access to laptop or phone (rare), and One Drive is my file collaboration solution. Although I like the functionality of One Drive, it can be frustrating if your IT team goes overboard on security. :) The single-sign-on we utilize at work keeps me signed in to all apps, and the applications load quickly and efficiently. Office 365 plus the 64-bit 2016 versions of the Office desktop applications is a great combination that I could not function without. I use Outlook, One Drive, Excel, Word, PowerPoint, Yammer and Skype for Business every day, so without them, I would be "dead in the water."
I like how collaborative Office 365 allows me to be on my projects. Currently, a co-author and I were working in real time on a project. I could see her typing and commentary while I was making corrections to the APA at the bottom of the page. We can also work asynchronously on projects, store them, and return to them. The ability to work in a browser ensures that I can review, make slight edits to the document, print and then save. As a person who is moving from one campus computer, to my computer, to my printer at home, to my office printer at work, this is about as fast as having a flash chip with me at all times, but I never forget it. It also integrates well with Citation software, similar to Word 10. We have a lot of files we share, and I like how easy it is to access from any location I'm at, as long as I'm logged into my university account.
One of the things I struggle with regarding Office 365 is what is the real difference between Office 365 and Google docs/sheets other than the price and privacy. At my university, Office 365 is free as long as you are a student or a researcher. As soon as I leave the school though, I'll lose access to Office 365, most of the work I've saved on the system. And while it's... nice? to have so much technology (meaning Access and the other programs that come in the suite) I never use Access but I "have to" have it. I wish it integrated better with my Google calendar so I could have an app on my phone but if that feature is available I don't have it.
if you are going to be a full time single user of Office 365, this might make sense if it automatically updates to the latest Word, Excel, Powerpoint, or Publisher. It would make sense to pay a yearly/monthly fee to continuously have Word rather than having to buy the expensive office suite every few years or so. But, if you don't need to update to the latest software, if you aren't someone who needs Word, Excel, Powerpoint, or Publisher to be at their most flexible, and if you get around on Google just fine, I don't know if it make sense to buy it as a single user. However, for large universities or companies which need flexibility, and collaboration for their employees, then Office 365 might be right for you.
I work on a lot of collaborative research projects and Office 365 lets me share files and reading and work with others. However, I really don't like their "calendar" system integration with Outlook, but I've never liked the Outlook calendar. I always use my Google calendar and I wish there was a way to sync those two, but as far as I know there isn't.