Rated 3 out of 5 stars
Worked reasonably well. My university has student e-mail on the same locked-down system as the hospital, so this was (I thought) the only way to get Office 365 into Thunderbird (or into Linux at all!). Unfortunately, it is buggy and the developer is caught between two rapidly-changing systems, Micro$oft and TB. TB upgrades often break ExQuilla. I also had occasional crashes and TB "hanging" in memory when closing. That, plus confusion over the free trial period, I bailed.
I have moved to using a DavMail gateway that was much easier to setup than feared and it works great on several devices.