We've been using sharepoint at my company for a few years now. As far as I know we don't use it to communicate outside the company but what we do use it for is a centralized network accessible location for (e.g.):
- Submitting expense requests
- Creating calendars of events that sync to outlook
- Repository for controlled non-engineering documents (SOP, Work instructions, Forms, etc.) It's also used for the document change processing of the same documents i.e. controlled documents are now solely electronic.
- Job tracking
- High level project tracking (e.g. milestone dates)
- Processing Non-conforming product (i.e. Quality disposition)
- Purchase Requests
- Contact/Supplier Lists
And a lot more that I probably don't see because it's not related to my position (R&D).
It's been a net positive but I'm sure there are alternative solutions.