How waterproof is a tent with a 1500mm PU coating, really?

It's enough for typical three-season rain if the seams are taped and the rainfly is properly tensioned, which matches what verified-purchase reviewers and r/CampingGear threads describe for the CAMPROS 8 and UNP 6. Reviewers consistently warn, however, that none of these mid-priced family tents are meant for sustained storms or high-wind exposure — a hurricane-grade weather front is outside what this category is built for.