Many folks have been critical of Apple's translucent menubar, slated for Mac OS X 10.5.
Personally, I don't think that they understand what it is for.
In my not so humble opinion, it is there to increase sales. Every Mac OS X release has made a change to the visual interface. For example, Tiger (10.4) added Spotlight to the menubar.
This way when the new, spiffy OS comes out, the former, previously adequate OS looks old and dated. Car manufacturers have been pulling this trick for years...