Completed all 4 seasons in 2.5 days. Seasons 1-3 were really good.. Slowly building up the overarching plot line. However, the final season, S4, was quite disappointing. It almost made me not want to recommend people watch this show. There's a sudden tonal shift, and a lot of really weird/dumb decisions made. The ending of the series wasn't terribly satisfying too.
Overall, seasons 1-3 really scratched the itch I felt when the Exorcist (TV show from 2016) ended after 2 seasons. The execution of the entire premise was a lot better here. However, Season 4 really left a bad taste in my mouth.
For new viewers, it might not be worthwhile to invest the 40+ hours into this show, unless you're cognizant of the fact that the final season is really subpar.