I can’t speak for Numbers and Keynote, but I have played with the Apple’s Pages 1.7 word processor with added MS Word compatibility. The app still changes almost all of the fonts in any imported Word document (probably due to font licensing), but the few imported files that I did try seemed to better imitate their .doc counterparts.
The real game changer here is the Track Changes feature, which works on both native Pages files and imported .doc files. The feature is still fairly basic – you can show markup, markup with deletions, or the final text – and it’s good enough to edit essays and other documents friends might send me. The only thing still missing at this point is review comments, but if Apple was willing to add Track Changes to the mix, I’m assuming that comments in the margins are just a matter of time.