It works for me
I've been using OpenOffice for most of my word-processing/spreadsheet needs for a year now, and I'm really pleased with it. I also have MS Office (2003) but I don't intend to buy any further versions. I'm tired of Microsoft's focus on lock-in (poor interoperability with almost everything else, dodgy compatibility between versions, tie-in with their own technologies and no one else's, etc, etc) rather than simply providing great software.
I also found I can organise quite complex documents without worrying that numbering/outlining/styles/etc all suddenly start to do weird things as they frequently do in Word (I can't count the number of times I've had to revert to older versions of Word documents because the current version has gone irretrievably 'insane'). OO hasn't been absolutely perfect either, but far more robust.
The most difficult thing was simply learning to use a new piece of software. Yes, almost all office suites are doing the same things, but they also have their own methodologies. I would encourage anyone to have a go at OpenOffice, but commit yourself to spending a bit of time getting used to it. And definitely check out the PDF import plug-in.
BTW - the reviews of OO on The Register seem really shallow. The previous one seemed obsessed with problems installing on Linux, and this one seems to think speed differences are really important. Can we have something more in-depth?