We use pure at our university to register publications. Maybe we also use it for other purposes, but I have only been affected by the publication part.
The registration of publications is a necessity, because the university uses this information to distribute money to different research groups (e.g. each year there is a bonus based on the number of published peer-reviewed articles in a recognised journal.
I've occasionally been assigned the task for my group to make sure all our articles were "registered in pure", and I can say that it works reasonably well. The interface is not superb, and I wouldn't like to work with it all day, but it gets the job done. I don't know anything about the alternatives.
It does also generate a fancy and completely useless person graph.