OK, would it be fair to say that Sharepoint sucks in roles that lots of people seem to expect it to be useful for?
Yes that's fair. Though IMHO most companies and individuals don't really use any of their software right. So for example the #1 thing people do with Excel is keep lists. There is far better outlining software than Excel which is much better for lists. But...
I'm hardly an expert, but I kept getting the impression that it was a bad tool intended for general use.
I think most companies (over 100 employees) need a document library. Most companies write a large percentage of their documents in Office. I think Share Point is a reasonable choice for a document library for most companies. That's the general use. Then you throw in project resources like team calendars, team wikis... I think it is rather good and less hassle than most of them. But that's different than saying no hassle.
Taking the example of a file share. What most people do with a file share is better done in SharePoint than NFS. Which is not to say Share Point makes a good no frills file share but the changes that Share Point induces are the right kinds of changes for most companies and will benefit them.
Similarly on things like project calendar sharing.