InfoWorld recently posted a review from their "Test Center" that looks at the latest version of Acquia's Drupal (v1.0).

As we've seen time and again, in an increasing number of enterprise software categories, open source has become a promising alternative to commercial software. But there's no free ride. Support from developers is often problematic, and you need to find products with a large enough following so that programmers have an incentive to build add-on modules. [...] Yet if you take support out of the equation, Drupal emerges as the better solution for many enterprise Web projects.

They point out some of the good (the power and flexibility of the CMS) versus some of the bad (the need for developers/admins with specific knowledge of the system) with a heavier lean towards the good. Other "goodies" they include are the robust installer, pre-integrated modules, like the Content Construction Kit and Mollom, and the ticket system built into the application for help with CMS-related issues (from Acquia).