I would move to Open Office in a heartbeat, but...
...for one member of the Open Office suite - Impress (the Powerpoint equivalent).
I use word processing and spreadsheet functions to a very limited level (as do most end users), but with Powerpoint I push it to the absolute limits.
When Microsoft release Powerpoint 2007 they totally screwed up by introducing the "ribbon" interface. Regardless of how good or bad this interface is, it turned their existing customers from "experts" to "novices" overnight.
I felt this was a fabulous opportunity for Open Office to establish itself as a serious alternative to Office. Open Office apps that retain the familiar look and feel of pre-2007 Office, and offer the same functions and performance should be snapped up by the market - especially because it's free!
HOWEVER...Impress is essentially unusable for anything but basic text slides. This is apparently (according the the Impress blog) because it does not take advantage of graphics hardware acceleration on PCs.
The result is that slide transitions and animations are jerky. Text and objects are initially displayed without anti-aliasing, and then visibly anti-aliased on screen for the audience's delight and amusement. I assume that the people who write Impress somehow don't notice, but to presentation professionals it's impossible to ignore.
I think the problem is that the people developing Impress tend to be developers (gosh, there's a surprise). But the people who use Impress are presenters.
But those developers also present slides from time to time. You've seen those presentations - they're the ones with a couple of hundred words on a slide, and lots of cartoon clipart images - good thing I can reduce that font size down to 8-point eh!
But Powerpoint has evolved not just as a text slide presentation package. It now contains a rich set of animations such that you can create quite complex, interactive "modules". As I say, I don't think I'm typical of the average Powerpoint user.
When I raised this issue in the Impress blog I was told "you should be using Flash if you want fancy animations". While I'm sure the person who wrote that is very clever at programming - he (probably a he) has completely missed the point.
There's a very real opportunity, given the gross incompetence and arrogance that Microsoft has displayed with Vista, OOXML, and Office 2007 for Open Office to establish a strong base of users. But to compete with Office you have to track both the features, and the performance for the whole suite, while returning the useability we enjoyed pre-2007.
I happen to be a Powerpoint "power user" (or I was before 2007 turned me into a bumbling eejit). I'm sure there are Word power users, and Excel power users who have similar concerns about the other Open office apps.