I'm currently playing around with Drupal a bit. First impression: wow! Extremely powerful, extremely many features. Though possibly too many features. But what I like right away is the very clean interface with quite logical menu structure, and how all extensions automatically hook into these menus. I also like the solution with templates and themes: themes can be divided into templates or stylesheets. This allows you to change the general system, but also just choose variants of a system. The default theme is table-based, but there's another CSS-based one to choose from. I can't really say yet how XHTML compatibility looks. Also good is the support for MySQL and PostgreSQL - I normally prefer the latter. You can also make weblogs with it, as well as static articles, entire books, stories with discussion forums similar to Slashdot or Kuro5hin and much more. However, what stands out right away is that the tools in the individual content areas are somewhat sparse - tools that specifically target weblogs often seem more complete. Specifically things like Trackback, Pingback, update pings or similar have to be installed afterwards or at least reconfigured - the standard only pings drupal.org itself for the distributed login mechanism. Also such elementary things as simple categories (more complex categories - even hierarchical - do exist, but elsewhere) for blog entries require some searching. RSS feeds are automatically created, but on some pages (for example the homepage) they first have to be linked (in user blogs the link is automatic though). Otherwise they are only contained as alternate links, but not necessarily visible to users. Overall, the whole system clearly aims to design and build entire websites with entire groups of users. However, the distributed login mechanism is really cool: users from participating systems can log into other participating systems with user@host and the login is automatically passed to the home system. Login with always the same password, but with distributed authorization. Very nice! Overall, a lot of value is placed on user management - it almost has Zope dimensions with its permission groups and the ability to create symbolic permission groups for individual activities. Less cool are the many missing metadata. There's actually hardly any metadata on content. Author, date, status - but that's more or less it (of course besides title and text, those are self-evident). Content organization is also left to the user - though there are helper tools that make creating navigation easier. However, many metadata topics (such as categories) can apparently be solved using taxonomies - these are groupings of content. The description of this is somewhat unintuitive, the topic is quite complex. Taxonomies are groupings of keywords on a topic. So I don't assign posts to categories, but rather assign keywords to posts and then organize the keywords into categories. While this provides mountains of metadata, it's far more complex than the normal blog categories you're used to.
Great again are all the content status and content versioning functionalities. All changes are logged. All changes to content are versioned. You can go back to older content and thus, for example, fix errors (or remove garbage from rogue users).
The whole system is extensible, but I suspect (haven't checked it yet, but given the range of functionality it's a likely guess) that creating plugins and filters is more involved than with small solutions like WordPress. But that's in the nature of things.
Another potential disadvantage is the unavailability of a ready-made German translation. While there are other sites working with Drupal in German, apparently no one releases the complete translation tables for download - at least I haven't found anything, neither at drupal.org itself nor on Google.
Where would I classify Drupal? Clearly in the CMS category - that's where systems like Typo3, Mambo Open Source, Plone and similar systems shine. However, it beats discussion-oriented CMSs like Scoop or Squishdot by a mile - as well as simple blog CMSs. For a simple blog system it's clearly overkill. For a complete site it seems very usable.