I mean, where are they now? Promising or DoA? I fear touching it because of it being a Google project (killedbygoogle.com)
As someone that’s using it, it is improving very quickly. Web support is getting quite good.
It has significant tradeoffs and fits some projects better than others.
React Native has quite a few benefits over Flutter. Especially if building for the web, I’d actually say Flutter is only usable now if you don’t build your web app with it. Which in my cost benefit analysis makes it miles behind RN, but of course, that’s why it depends.