The Purge has come a long way since its inception. Originally used as nothing more than an excuse to explain away "Why don't they just call the cops?" in your average home-invasion movie, the original Purge movie had implied classism for the meat of it, and then an actual call to class division right at the end. Since then, the classism, and racism in American society has become a focal B-story to the Purge movies, and now we're in 2018 for the prequel - The First Purge - and those issues are now the whole point of the movie. Some might say that it's because the movies have lost any sense of subtlety, personally I think it's more that the creatives are sick of people missing the point.
The First Purge can't have been an easy thing to give the go-ahead in the current political climate over in the US, but it's important, and moreover, not a bad little film, socio-economic politics aside.
Final rating:★★★ - I liked it. Would personally recommend you give it a go.