Reactive programming enables amazing things. Highly scalable systems consuming just a fraction of CPU compared to ordinary applications? Sure. Responsive, low latency and high throughput? No problem. Small memory and OS footprint? Out-of-the-box. Any reason not to love reactive? I will share some of my experiences with reactive programming and systems. Where it shines and where it was an over-engineering. What are the hidden costs and common mistakes? How to convince your teammates to start the reactive journey. And more importantly: how to convince your teammates, that going reactive is a dead end. On a case-by-case basis.