One of the contributors here - not entirely sure if you're asking for pros or cons, but the entire point of Caldera is to execute/keep the React code on the server and only stream DOM updates. It's set up such that existing React web apps can be easily ported over (essentially just move all client logic to the server), so you can definitely make normal web apps with the framework! If you're asking about drawbacks, one of the biggest issues is latency, since events need to be sent to the server to be processed, but this can be relatively easily alleviated by hosting servers closer to clients.