Content Management Systems (CMS)
I started playing with Drupal a while back because I wanted to see how one of the other Open Source CMS worked. I'd been thinking about building a site called blackberrybooks.org and decided to use Drupal for it.
I'd purchased a copy of Using Drupal and noticed that it contained a chapter on building a product review site, so I knew I had exactly what I needed. I dug into the book and carefuly crafted the site I wanted and when it came to the section where I was building the views I'd need to display the book listsings, nothing worked. Every time I followed the steps in the book (step by step, I promise) I'd reach a point then start getting errors. Drupal has an automatic update notification feature, so the site sent me an email letting me know that there were updates available for the Amazon plug-in I was using so I installed the updates and tried again - no luck.
The problem with Drupal is that although there are a ton of plug-ins available - very few of them (or at least very few of the ones I was using) have any sort of documentation. It's too bad, but as you probably know geeks just don't like writing documentation.
I gave up and built the site using the Book Library module for Joomla. It took me about an hour to completely build the site in Joomla. I hope I get another chance to try Drupal again - it's an amazing CMS, much more flexible and tunable than Joomla.