Or, depending on who you ask[0], precisely the opposite.
[0] http://www.youtube.com/watch?feature=player_detailpage&v=iwx...
I often use PPT to lay out simple diagrams, for instance, in preference to Illustrator.
I could see how some things can get on your nerves (auto-formatting, reformatting of pasted objects, and I don't like the spelling and grammar check either) but I couldn't call it infuriating. And it did not approach using OpenOffice. I think you must be exaggerating there?
There's just so much about it that's "not right" -- it doesn't feel like a Windows program, doesn't feel like a Mac program, performance issues... it's hard to point to any one thing, but it's just not pleasant.
(Whereas I used Office on Windows for years, and it was great.)
Just a random example, this morning I was trying to use Cmd+A to select all the text in a field in a dialog box, which kept activating a button which started with A instead, and there wasn't even a visual cue for it. That's not Windows OR Mac behavior, just totally broken behavior. And it's just full of those things.
It's really bizarre all around. Surely they don't want it to suck for the purpose of driving people away from the Mac... wouldn't they just want people to use their format?
I wonder if Word:mac is the bastard-child of corporate conflicts of interest...