This is worth the read. Check out Jeffrey Veen's critique of open source CMS's which makes some excellent points, some of which apply to Drupal. Note that he does give them credit for being better than their commercial counterparts:

"Open source content management software sucks. It sucks really badly. The only things worse is every commercial CMS I've used. But it really doesn't have to be that way."

For those that want the short version, here are the key points:

• Make it easy to install
• Make it easy to get started
• Write task-based documentation first
• Separate the administration of the CMS from the editing and managing of content
• Users of a public web site should never -- never -- be presented with a way to log into the CMS
• Stop it with the jargon already
• Why do you insist Web sites have "columns"?

Update October 5: Dries offers Jeffrey Veen a deal:

For each hour you or your company Adaptive Path spend reviewing Drupal 4.5.0's usability (free of charge), I spend 4 hours implementing your suggestions (free of charge). The review should be public, and the Drupal community should be behind the proposed changes. If you don't feel like setting up a Drupal site yourself, I'll set one up for you.

Update October 7: Jeffrey Veen responds.