And the converse is true too. Any properly designed PPT or ODP fails on other office suites, because you just designed it with stuff that is implemented either differently, or absent.
Then I might as well use the best tool available to me, and that's Keynote, hands down.
If one collaborates to produce a presentation across suites, you should focus on content and use the common denominator, which works perfectly fine. If it's distribution problems, well, sharing a presentation is always lacking. Slides by themselves miss most of the content. Anyway, Keynote has an interesting export system which creates an MPEG 4 video with chapters and stop points. That's the only way to produce a result with 100% accuracy (unless you design your slides in HTML5).
Sure. Why do you expect that to work? The import/export is obviously only for emergencies. You should never try to integrate it in workflows with other office platforms. That's true for every single office platform. There is no way around that.
Ok, then it's not for you. Simple. LO is an Office clone, something iWorkdoesn't even attempt to be. I don't want iWork to be an Office clone. LO sucks because of that. (And import/export is far from painful.)
S/he switched, so it was not for her/him. S/he spent some money on things you kinda expect to work, s/he may have the go to say why s/he switched and paid the price for not knowing beforehand, literally.
I love iWork! Keynote is a masterpiece!