Syntaxually and philosophically. Implemention-wise it's more like MobX or Vue style reactivity without a Virtual DOM. It takes compiled reactivity past the localized component model of Svelte to new(ish.. the library has been around for a few years) heights in flexible templating with JSX and unparalleled performance.

The update cycle is the exact opposite to React Hooks. With React your Component needlessly re-renders over and over and your Hook dependencies explicitly whitelist change. With Solid your Comoponent is a basic function that executes once closing over state with it's Hooks, which are the only thing that run over and over as needed when state changes.