I've been using Svelte at the day job for almost 3 years (coming from a React background). We're using it for a pretty large application that's probably going to end up being at least 400K lines of code. I love how you can leverage CSS to visually indicate state changes:

  <script>
    export let selected;
  </script>

  <style>
    [aria-selected] {
      background-color: blue;
    }
  </style>

  <button aria-selected={selected}>Click Me</button>

You can't do that with React. The lack of a VDOM is incredibly refreshing and I don't notice any performance issues.

I occasionally come across articles expressing concern that it won't scale up for large applications and I find that confusing. React has considerably more footguns than Svelte. I've ported over several personal projects from React to Svelte and it always shaves quite a bit off the line count and makes the code less confusing (at least in my opinion). Granted, it's not perfect. Forwarding props is kind of a pain in the butt and the docs advise against using `$$restProps`. There's also some trickiness when it comes to overriding styles. The only way to override a certain style in a custom `<Button>` component is via a `style` prop, using CSS Modules, or a CSS-in-JS library like Emotion. I've been using Vite's built-in CSS Modules and it's working pretty well.

The scoped styles are really nice. If you structure your components right, make sure you're adhering to accessibility guidelines, and use semantic HTML, you can usually get away with styling the markup based on the element type or attribute without having to define classes on the elements.