The flame bait of the moment, usability must die has a page on why AlertBox is nothing but NNG propaganda: The Day Alertbox Died.
Unfortunately his statistical evidence is based on a poor assumption… that how many links and where they link is a representation of how effective an objective critique of usability Nielsen is. That would be like saying Metafilter is more objective than the New York Times, because it has more outward links. A link clearing-house is not the same as a content producer, and alertbox should not be judged on the same scale as the very excellent but very different webword.
None the less, alertbox has been all over the map lately, from wildly inaccurate to insightful and useful. not sure what is going on in the head of Nielsen.