I've been playing with Drupal forums quite a bit lately for TraumaAdoption.org, a site for parents of Children of Trauma. The discussion forums are a focal point for the site for parents.
Drupal's core module "Forum" is basic. It uses the node and comment system to allow for conversations but not much more. The look and feel isn't like other forums like vBulletin or phpBB and users may have some difficulty getting used to the interface, particularly if your participants have used other forum systems in the past. There are, however, a plethora of contributed modules that can help improve the user experience.
These include (available in Drupal 6):
- Advanced Forum - It alters the look and feel of your forum to act in a way much more like stand-alone packages like vBulletin or phpBB.
- Forum Thread - This gives your users a nested view of topics in a single view.
- Signatures for Forums - Gives your users the ability to add a signature to all posts that they make.
- Nodeforum - This allows you to take advantage of having forum responses act as nodes in and of themselves. Nodeforum is dependant on Node comments.
- Forum Access - Allows you to set up private forums and also give admin access to users in individual forums, essentially allowing you to set up moderators on your site.
For me, there are two things that make Drupal forums extremely appealing.
- They are very easy to setup and integrate seamlessly with the rest of your Drupal site-no need for single signon.
- They are indexed with the rest of your site for the purpose of search.
One thing that I don't like about Drupal forums is the treatment of responses to a topic. The module uses comments so they won't end up in your xml-sitemap (if you are using the module) as new content. I expect that this could be rectified if comments are nodes, but that increases overhead. In addition, I've not had a whole lot of luck setting up Nodeforum--the forum specific module for this purpose--in Drupal 6.
All things considered equal, utilizing some contributed modules, Drupal forums are pretty appealing.