Drupal is a quite capable platform, and I've used it quite a lot, both for work and for personal projects. Its Achilles heel though is the admin interface - with ultimate flexibility comes a lot of configuration choices. While the simple solution is to tell the client 'just don't look at that stuff' - it's not ideal, and can be intimidating. Enter some key modules: jstools, form_store and formfilter. This combination opens up a whole new world of functionality, most of which I haven't touched yet. However - one fantastic benefit is the ability to filter forminterfaces. When you enable this feature and allow form filtering for a role, you see a link to 'filter this form' under any form element.
When you are in the 'edit' view for a node, you can hit this link and then you are presented with the edit view, but with a checkbox under each element that, when checked, will hide that element from any other user who does not have access to the 'filter forms' functionality (set via Access Control). The admin interface could still use some work, but this goes a whole lot of miles further down the road towards a really useful, usable solution for the site owner.
There are some occasional issues with fieldsets not being expandable, so it's necessary to test thoroughly to make sure that you have a combination of featurs available that works well, but on the whole it's been an enormous hit for us.
I should also mention that we've been working exclusively with Drupal 5 (specifically 5.15). I really like the looks of 6 but there are still some modules we really like that aren't there yet. Soon I hope!