I basically think of it like something like emacs, where it doesn't conform to the OS at all but instead works exactly the same throughout different platforms (and users who are intimately familiar with it expect that). The interop in Office for Mac was also just about as lousy as Pages for a long time although I think more recent versions may have improved it.
I don't think the two are comparable. Emacs is a bizarre beast that fits no common UI paradigm/design language/whatever. It has its own shortcut system, its own undo/redo behavior, its buffer concept, etc. Everything about it is EMACS. If you use Emacs, it's specifically because you want to use Emacs and all it's uniqueness. It's consequently a love-it-or-hate it tool, and it's extremely niche relative to Word, or I bet even gedit.
Office, on the other hand, you probably use because you need to create Office-formatted docs. Very few people are likely buying Office because they long for the Office interface. Office doesn't even have a consistent interface paradigm. They've reinvented it repeatedly, culminating in the Ribbon UI. But at the end of the day, Office's interface is a Windows interface. They've done their own thing, but it's still clearly Windows, and shoehorning that interface onto a Mac feels out of place in a way it doesn't on Windows.
I can't comment on interop. It's been a while since I used Office for Mac. I don't recall any notable interop issues, but I mostly used the mail client (Entourage, later Outlook). I used Word sometimes but wasn't exactly writing for publication.
I guess I use Word in a different way than most? I used to be a major user of advanced features like the VBA editor, style editor, etc., and having that all work totally differently bothered me.
If you just want .doc files lots of programs will do it cheaper.