I just started understanding GameMaker just as the transition to 2.3 started. I didn't realize so many assets were becoming outdated or incompatible, especially with HTML5.
There are more complex, feature-rich, or efficient lighting packages out there, but the balance of simplicity, usability, and performance make this one a winner.
This is a great way for someone less familiar with shaders and lighting to apply some creative thinking and get effective results.