iOS works well when you want solid control over institutionally-owned devices. This generally works best when you play by Apple's rules and buy through them and use Apple School/Business Manager - so if you're going for a BYOD model, this probably isn't the way to do [it]. There is a wide variety of management tools, but bear the costs of each in mind.
It is well suited in a work environment, being that an organization can set up their system to be specifically work related and only certain users can get access is really helpful. I also like that multiple users can log in on the same device and keep each account seperate without interfering with the other.
In all likelihood, common users will either already have experience with iOS on their iPhones, or will pick it up quickly. The UI is generally simple and mostly visual. Power users, on the other hand, may feel constrained by the inherent limitations built-in. Root access, terminal commands, and deep customization are not really to be found here.
Lots of help articles online for just about everything under the sun. I have never personally had to engage Apple's support team to comment on their helpfulness.
The software updates have a wide coverage for iPhone models and I love updating software for additional features and/or improved software stability. It has also genuine feel of the phones they offer. Easier to set up and use. It helps me do more productive tasks. If I have the latest phone model, I would have additional software advantages that are already included in my OS.