The five most important takeaways from this course, in my opinion, were
1) The use of GitHub projects. I believe this will come in very handy for future jobs and also personal projects. It gave me a taste of what it is like to coordinate code with a group and resolve potential conflicts.
2) The Agile philosophy. Agile seems to be a trend with how companies organize projects these days and I know that many employers that I've been in contact with so far prefer a candidate with experience in the methodology. Learning the concept of iterations and sprints and how they relate to organizing a project is going to be invaluable for me on the job.
3) Code reviews. So far I've mostly worked on projects solo or with a single partner. Seeing the process of code reviews and how they can be used not only to comment on code functionality, but code design and even documentation is something I'd never really thought about in the past.
4) TDD. While I've always known that testing was an important part of software design, the idea of writing tests before implementation is very interesting to me and I can see how it would lead to better functionality. Any time I've written a test in the past, I've found myself having to refactor code in order to be able to test it in a way that makes the most sense. I think writing the tests first could make my code cleaner and save me a lot of time.
5) React. I have a major interest in web development and knowing React could prove invaluable to me when looking for a job. While I don't find it as intuitive as I found Node.js, I loved figuring out the interactions between the components and seeing how they came to life on screen.