I'm cynical about this article feedback system for several reasons, chiefly the worry that it could exacerbate the templating trend of commenting on lots of articles rather than actually improving a few.
I'm also slightly circumspect about the idea (though not outright opposed or anything).
The issue I've noted is that it is being used as a "warfare" tool on controversial articles. I've not seen it mentioned on a talk page yet; but one contentious article (on a subject with a large online following, entrenched *readers* on either side of the issue) has had the bars swinging between about 1.5 and 4 in the last week.
Not a huge issue, but I suspect that on certain articles the ratings are to be trusted less than usual :)
Tom