I've been spending so much time in Drupal lately that I've been contemplating moving my blog from WordPress to Drupal to take advantage of some of the flexibility in Drupal. I've even gone as far as migrating a copy of this blog, and it's basically working now - it may even look familiar.
But, I'm holding off on throwing the switch (I came within about 5 seconds of a full switchover, but finally decided against it). Why? WordPress is still nicer for individual blogging. Sure, it lacks the super-handy Book structure. And the better Menu and Page management. And a bunch of other cool stuff.
Drupal has far better searching - advanced searching with booleans - and better ways of organizing content (multiple taxonomies, tags, paths, etc...). It has better "website management" and a pretty decent upgrade process.
But, WordPress (for now) has better integration with things like image uploading, Flickr images, podcasting (via PodPress) and a bunch of other little things that tie into the "workflow" of blogging, as opposed to content management. These are all things that I use my blog for now, so it's silly to switch to something that doesn't currently rock at doing these tasks.I'm absolutely confident that I could eventually bend Drupal to do my bidding, but WordPress already does it now, so there's not a Super Compelling Reason To Jump at this particular moment. Also, the migration process isn't the smoothest one on the planet, and appears to be a one-way trip.
Update: I mentioned in one of my comments to this post that I was afraid of using the WordPress DBook plugin, because I didn't want to introduce any non-standard content types. I was completely wrong about what DBook does. It's sole function is to do the heavy lifting to provide better inter-page navigation between WordPress Pages. No new content type, no change to the database at all. Sorry for not checking facts better before posting that comment!