Event Sourcing is a more frequently heard buzzword, but is it solving all our development problems, or is it introducing new ones? Let's see it in practice! Event Sourcing can look like an attractive solution for any of your applications, but does it actually pay off? What if it is all just buzzwords and no gain? We’ll look at how we implemented event sourcing in our own app, code-reviews.io: what made us fast; what made us super slow; what made us cry. This talk will give you a good idea of what kind of challenges you will encounter when approaching event sourcing for the first time.