I remember getting really frustrated with GPOs before I started digging into more of AD, but I can't remember having any major problems with in the past few years. I imagine most of my problems were with misunderstanding scopes and/or not realizing how long it takes for things to sync between DCs.
If I've learned anything from SwiftOnSecurity, it's that GPOs will still run even if you've thoroughly borked just about everything else, so if you're having trouble, I'd double (or triple) check that you're applying your policy to the correct place, and that it actually applies to the correct computer/user section.