Happy (self-hosted) Grist user for almost 1.5 years here !
Working for a government agency, self-hosting was an absolute must for my team and we're just loving the product so far — and have been contributing a lot to it in return (they are very serious about really playing the open-source game!)
What I love the most is that the way it's build makes it easy for anyone familiar with spreadsheets to get started while making virtually anything possible for a more technical person through custom widgets (basically a web app that integrates with any table and is displayed within Grist) and python formulas !