I took this course because I wanted to learn about the payment domain. While the content is good, the teaching style felt like simply reading off a script, and there were many frantic moments where I had to just watch fast-forwarded code writing. My disappointment is as great as my initial expectations. The Q&A section is also not being managed. I will revise my review after completing the course. I believe the following prerequisite knowledge is necessary: (R2DBC, WebFlux). As for Kotlin, if you have extensive experience with Java, you won't have much trouble reading it.