Yeah, well, although it's a server side VDOM, so it's more like React/Preact, but 100% server side.
It's quite different from Rails. There are no models, no views, no controllers. There are components and there is a directory called app/pages where all components named page.haml will get their own route (kinda like the path based routing in Next.js).
Ruby+Haml removes a lot of unnecessary syntax so components become much shorter than their JS equivalents. It feels really nice to use actually.
Since the server knows which components are in use on a page, it will only include CSS for those components, which makes loading pretty fast. Then whenever a user clicks on a link they will receive the styles for the components that appear there.
There is no need to write JavaScript, nor is it possible. It would be interesting to support custom elements (web components) but I haven't found a use case yet. I suppose it will come up some day, for things that need to be aware of browser state like scroll position in very long lists.
It's really easy to make interactive components, just like React. I'm running the website on Fly.io and I barely notice the latency (I got about 60-120ms and my nearest edge node is in a different continent).
I feel like I'm up to something good, though I'm gonna need to attract some users and contributors to make it usable. There are a few bugs and lots of improvements to be made... But it works!