His usability comments are a collection of various rants with some reasonable comments mixed in. Complaining that Gnome isn't Mac OS (e.g. his first comment about wasting space by every window having a menu rather than a single one at the top of the screen) is rather stupid. Commenting on the font colors for active versus disabled text is fine. I would send his comments back for a rewrite if I were his editor.
In short, wouldn't hold that up as a good UI review myself.
I downloaded the 5.04 install and live CDs yesterday with the intention of trying them on my T41 (previous attempts with Ubuntu were unsuccessful). If he's representative of the folks at Canonical working on Ubuntu, well...
Cheers,
Scott.