React works well until you try to avoid re-rendering and then it really falls appart. For example, updating a context re-renders the whole component chain from producer to consumer, and trying to block useless re-renders with shouldComponentUpdate easily leads to mistakes where children don't update when they should. Since React rendering use lazy evaluation of JSX expressions, tracking who exactly updates and when is much harder than what it might seem initially (akin to tracking mutations in a language with lazy evaluation). As this library actually tracks dependencies and only re-renders what you want, all of this bloat is avoided. One aspect that impresses me in particular is that JSX expressions actually return real DOM nodes, making it easy to keep references to them for imperative operations (not a big deal but so much nicer than React refs).
I'm wondering why you opted for the setState API rather than a nicer imperative API like Mobx. From what I can gather, state changes are tracked by diffing? Why not just return a proxy?