I like how easy is to set up an alert whenever something goes wrong in my infrastructure, as well are all monitoring metrics that you can track through out your day job! The UI needs some improvements but it's getting better every month since their last update (in May). Also they have released new features lately which helped me solving problems while developing our first Production application with them: such us integration of custom dashboards or alerts when certain conditions met using AWS S3 event stream API; also adding support for Prometheus Operator/Operator SDK was really helpful because we could integrate this tool into Jenkins workflow very easily without having any knowledge about configuring PromQL queries etc...