I'm working with Lit daily since 2 years (medium-complex B2B SPAs) and it's mostly a very positive dev-experience. Sometimes, Checkboxes and Selects won't rerender correctly if their state is modified from outside, but that's more intrinsic to the way custom elements work. No problem though once you get used to it and have your workaround. It's all standard HTML in the end, so you can always hook into and change your elements manually.