1. Drupal allows us to integrate all the different sections of the site together giving us the advantage of a single sign on for the whole site. Before we had a different accounts for the blogs and the forum which could easily be confusing for people expecting to be able to use their account site wide. This can be extended soon with the Drupal integration of Open ID and when we come to upgrade to Drupal 6 in the coming months this will be even easier.
2. Templating and management - This is more an advantage for me but does help consistency throughout the site. Before I would have to write a number of different templates for Wordpress and PHPBB, as a result each would look slightly different and behave slightly differently. PHPBB was especially hard to template and the code on my part always ended up messy with various hacks. With Drupal we have one template and all sidebar widgets can be put in blocks meaning that once the basic template is made everything can be added into blocks within Drupal (rather than editing template files).
From a management point of view the advantages are that everything is centrally managed. I can monitor all content, comments, spam, security problems, 404 issues etc from one area. Before I used to have different logins for the different parts of the site and it was hard to see if people were getting errors.
So far in the last couple of days our 404 (page not found) page has been one of the most popular, with the new site I can see why people are getting to this page and setup redirects to fix problems and customise the 404 page to be more useful.
3. Spam has been an issue on the Forum for a long time and last year caused us to stop allowing new members. The Blog used a service called Akismet to remove spam very sucessfully however this was not available for PHPBB. Fortunately it is available for Drupal so that the whole site can hopefully become spam free.
4. PHPBB development is slow which in some ways is good as it means less upgrades for me. On the other hand it means it misses out on new features. In the past five years technologies such as RSS feeds have come along and left PHPBB in the dark. PHPBB 3 fixes a lot of these issues but after we trialed it there were missing features we were already use to (such as quick posting). The decision boiled down to upgrading to PHPBB3 or migrating to Drupal we opted for the latter.
5. Wordpress development is also slow but the software is feature rich. For anyone with a single blog I would highly recommend Wordpress as the best blogging platform in the world. Unfortunately for our multi blog layout and forum it was a necessary sacrafice.
6. Drupal's development goes at a quicker pace but because it has more general uses than Wordpress or PHPBB it needs to be. By moving to Drupal it opens up a lot of options for the future such as the integration of E-Commerce (for Switchweb), galleries, Wikis and many other modules that can expand on the current site and content.
7. By merging all the content in one place its a lot easier to categorise and produce custom views on data. For instance I can easily create pages with the most popular posts (such as the widget on the right) or most commented posts. This would be very difficult before.
8. The front page can reflect everything that is happening on the site from blog posts, to articles, to extra posts, to the forum and as such content will flow much quicker and easier through the site.
1. People inheritantly do not like change, especially the sort of change we have experienced over the past week on ImAFish (new design and functionality). Fortunately 75% of our visitors are new so wouldn't notice the difference between old and new. Reoccuring visitors will notice a difference and will likely experience some usability problems (particulary on the forum) until they get use to the new system. I saw the same problem when we moved to ImAFish X however over time people will get used to it and hopefully find the new system easier to use.
2. Parts of the functionality are still being finished off and I will admit its going to take a couple of weeks to get everything perfect however I feel it will be worth the hassle and time.
Many of the things I've described here may be available elsewhere or within Wordpress/PHPBB however Drupal makes it easier, quicker and more efficient.