10 Reasons for using DRUPAL Advanced URL Control Custom Content Types and Views Revision Control Taxonomy User Management Page Titles and Meta Tags Excellent Documentation PHP Template Drupal Cookbooks Large and Friendly Community
There are some more advanced tools: Rules Context Tokens ... Drupal is very modular. I would disagree with "excellent documentation" and "easy to use".
The main reason why people use Drupal is Powerful. Drupal is more than a CMS -- it's an information management system. In addition to simply being able to edit your web pages and post new articles, our customers find it replacing lots of other in-house systems, such as Access databases, Customer Relationship Management systems, project management systems, and more. Drupal is a great development platform for all kinds of business systems -- and it happens to come configured for content management out of the box.
I just wish there were better looking themese for drupal for business. Even mosy of the paid ones just lack the flare of most of the php sites. Even removing the jquery, html usually looks better when done right. But god it is easy to use.
I Thinks Its themes are very high and content cab be customized. It is easy to use, SEO friendlly. It has better quality tools like Rules, Context, Tokens. It can be easily used and hundreds of modules.
I likes Drupal! I prefer to create my websites in Drupal theme and have lots of websites having god position in Google ranking. Drupal communities delivering wonderful service that has great appreciation in market. Its modules are user friendly and easy to follow. There is nothing complex I found ever in Drupal operating.
The reasons I use Drupal are : 1. Hook system & alter functions 2. Plenty of samples, snippet, tutorial in the internet 3. Powerful template system (which is also confusing and complex to learn) 4. Renderable arrays, modify the array before template process them 5. Form API, write form without touching HTML tags 6. Easy to use AJAX system (for Drupal version 7, for Drupal 6, welcome to AHAH nightmare) 7. Taxonomy system 8. Powerful permission system for access control The reasons I never recommend Drupal for small sites : 1. Super bloated and slow, not recommended for shared hosting 2. Since Drupal is DIY tools, bad site builder = NIGHTMARE to maintain or fix 3. Its expensive to get a really professional Drupal coder 4. Need much much more hours to build a proper working Drupal site comparing to other CMS 5. Hard to teach newbies or non GEEK (read : client) on how to operate the site. Bottom line? If you love to code, love the command line (Drush anyone?), love to bill your client based on hourly rates, got a big company to back you up, love complex thing... then Drupal is your soul mate..