O365 University user here, distance learning with UK Open University. Whilst my main word and note taking is done on a Surface Pro 4, the Office suite on iPad Pro 10.5 is sweet. Some of the more advanced formatting and ink to text/ink to formula is not as feature rich as desktop Windows Office, what is here is absolutely sweet. Making up notes in OneNote on the iPad is great, as is using it as a large e-reader for revising from notes, embedded PDFs etc.
Word is more than good enough for text entry/essay writing with the Smart Keyboard Cover, with final formatting etc left to going on the desktop.
if you've used O365 via the web, O365 on iPad Pro 10.5 sits between O365 web and O365 desktop. More features than O365 web, plays nice with iOS 11 multi-tasking/drag & drop, but not quite as rich as O365 on the desktop.
Having all of my notes and docs hosted on OneDrive and being seamlessly available everywhere would be worth the yearly fee to me anyway, even if I wasn't on O365 University. Office and its integration with OneDrive is one area where Microsoft truly excels. Pun intended.