Drupal is a free and open-source content management system written in PHP. When determining whether Drupal is a GOOD technology to use in general, there are three main aspects we need to consider.
Drupal needs to be: Efficient: How does this software use my server’s resources? Does it use them wisely or am I going to run into speed issues or concurrency problems early on? Reliable and Robust: Is the code clean, or full of bugs? What is the impact on my site if I have to constantly add patches or get updates for faulty code? Flexible: Will I be able to implement changes without starting over from scratch if what I want/need from my site changes later on? Drupal will always be a work in progress.
Even so, it is a given that the source code used to build your website has been well designed and meticulously crafted. The three specific points listed above are taken very seriously by the developers of Drupal (it says so in their “set of principles” available at http://drupal.org/node/21945.) Drupal code itself is very well designed and written which makes modifying it easy.
As you try more advanced tasks, the design of Drupal alone will lend you an advantage over other platforms.