While preparing for job hunting, I was struggling to create a differentiated portfolio, and this course became the answer. The experience of cloning the Express engine myself is an excellent topic for demonstrating technical depth even in interviews. It's very practical that the course doesn't just stop at implementing features, but covers security considerations like MIME type detection and path manipulation prevention, synchronous/asynchronous error handling, and even test automation scripts. Particularly in the part about improving architecture using Singleton patterns and IIFE, I was able to deeply consider code quality and maintainability. For those who have taken Part 1, the foundational course, there's a lot of content that will make you slap your knee in realization. I strongly recommend this to aspiring backend developers who want to learn 'properly'.