The MS Office 365 Mac user experience
After using MS Office 2016 on the Mac for almost a full year, I can tell you that Microsoft of 2016 is not the Microsoft of 10 years ago. The Windows only focus has been left behind, and replaced by a strategy of delivering a (pretty) consistent cross-platform experience, encapsulated in the Office 365 brand.
I believe the change in Microsofts strategy is most profound for users of their office suite on Apple platforms. The evolution of the look-and-feel of the Mac Office suite is just remarkable. The previous Mac version, Office 2011, was a real UX turd. The new version, Office 2016, is significantly improved with regard to design, functionality and stability. Although, a diehard Apple fan will question some of Microsofts design choices, like: Why use a floppy disc as the save icon in 2016?
So, the native apps are great. But, what about the online apps that are included with an Office 365 subscription?
If you are using the Safari web browser, you are not going to be pleasantly surprised by the online experience of Office 365. Even though Microsoft lists Safari as a supported browser, there are things that work Chrome that does not (yet?) work in Safari. One such (really annoying) thing is that in Safari you cannot move tasks around between buckets in Microsoft Planner. Given that Safari is pretty much a standard compliant browser, the underlying problem is that Microsoft is just not trying hard enough to be fully cross-platform with their web-services.
Talking about bad things. The initial experience of setting up Office 365 using the admin interface is not pleasant at all. The interface has a number of irritating bugs, and wait times for server responses to complete are excruciatingly long. The first run admin experience is something that Microsoft should be able to easily improve on.
The online versions of the standard Office applications are usable, but they do not seem attractive to use on a daily basis, at least not when compared to the desktop versions, or to competing web-based products, such as Google Apps (or G Suite, as Google Apps is called now). If you are into writing long documents in using your web-browser, I would recommend G-Suite over Office 365.
An Office 365 business subscription comes with a lot of extras, most of which you probably won't need, unless you have people employed that have a lot of free time during their work day. The extras are: Planner (a poor mans version of Trello), Yammer (an internal Facebook-clone for your company), Delve (search interface for your OneDrive and Sharepoint files), Sway (something, something, fancy online presentation, not even going to try to use it).
Back the desktop. Besides the standard Office applications (Word, Excel, Powerpoint, and Outlook), an Office 365 business subscription also includes OneDrive with a terabyte of storage. That sounds good. But, before you cancel you Dropbox subscription, you should know that OneDrive for business is not anything like Dropbox. A file you put in OneDrive is synced to the cloud, but if a co-worker shares a folder from their OneDrive, the shared folder is available through the web-interface, but can not be synced to your Mac! Apparently, Microsoft is working on fixing this (major) deficiency. But, if you are a Dropbox user, you should hold out until this is fixed, before switching to OneDrive.
In summary.
The Office 365 web services doesn't work well with Safari. They work reasonably well with Chrome, if you don't mind the waiting for Microsoft's servers to respond.
The Office 2016 desktop apps that you install on your Mac (or on iOS devices) are really great, and a big step up from the Office 2011 experience.