Being a newuser/admin of Drupal I would say a few things.
Like any new system of the size and complexity of Drupal there is a learning curve. The way Drupal is built uses good design principles and the system is built on the concept of nodes (be it a forum node, a page node or book node etc.) - some may prefer another approach but this is the way Drupal works.
It works well; as a system designed to be set up by web designers/admins (not users).
It has a very active community, the support is second to none for an opensource community effort (response normally within an hour in my experience!).
Weaknesses in my humble opinion are:
- Not enough focus on the individual (i.e. user). A community oriented system should centre on the individual, not the content; on the other hand, this was designed as a cms, not a community system, so that being said the latest release goes a loooong way towards a community goal - the will appears to be there
- The terminology has been (and still can be) the hardest learning curve. That being said I had it installed within an hour of downloading it having never implemented a cms before - piece of cake really.
- Configuring was tricky (not so much the doing, but understanding how to), but in the latest version (Sept) this has been addressed 100 fold (with lots more integrated hints etc., ....and so has it seems (at last) the drupal.org web site with a face lift.
- Documentation is pretty good, but misses some things - where it lacks the forum usually has it.
Summary - for a system that can be molded for so many different uses it is very stable and in my book very user friendly. It only lacks the marketting machine.