Hi. I was a HUGE fan of the first season and I never watched season 2 because reliable people were saying it was just pretty meh and - in particular - that it didn't have the Ligotti/Lovecraft/Chambers vibe and elements which for me really elevated Season 1. I never even knew there was a season three.
So without spoilers, should I watch S3 and S4 of this show? Specifically: Are they (a) good and (b) do they reintroduce the subtle occultism for the first?
No, there's no philosophy or occultism even hinted at in S3. S4 is Night Country which just came out, I'm not even sure all the episodes are out, I haven't really checked on it because it looks like retarded DEI girl power bullshit - although if occultism is solely what you're after, it is probably in there at least as an aspect, since muh Indiginous Americans or whatever.
S2 actually does hint a little bit at occultism, but then it's very quickly explained and brought down to earth, it's not omni-present or a factor of the murders like in S1. However S2 has great performances from Colin Farrell, Vince Vaughn, and even Rachel McAdams (not to mention a slew of great character actors and bit parts). In particular Colin Farrell is hilarious with his "son" and Vince Vaughn has some great damn lines throughout the series. Unfortunately, outside of those two characters, it's pretty tropey (although well done) and the story is waaaaay too far-ranging for an 8 episode series. I think the biggest problem is that there's too many "main" characters, and they don't spend enough time together to build up chemistry like the two leads in S1 did. That, plus a somewhat disappointing and stupid ending kind of take the air out of the season. On the other hand, if it was just called something besides True Detective, I think it would've been received much better.
I still think S2 is very much worth watching, especially compared to the vast majority of shit that comes out, but other than having a sex-related murder and a couple detectives in it, it's just too far removed from S1.
S3 kind of gets back to its roots, having just two leads who spend enough time together to build up some chemistry. Unfortunately for me, one of those leads is Mahershala Ali, who I think is terrible in all aspects - unbelievable as a detecive, a soldier or even an old man. Stephen Dorff is, on the other hand, absolutely terrific in literally the only role I've ever actually remembered him in and associated with him. The murder and cover-up are much smaller in scale than the first or second season, and there's not even an attempt to hint at something grander or darker (which is fine, it's really not why I don't like this season). I think for me the mains are just uninteresting; I mean in S1 you had Rust and Marty have good arguments about shit from their own perspectives, S2 you had Farrell and Vaughn as very non-tropey characters who were either in interesting situations or had great lines. S3 just has kind of bog standard detectives trying to solve a crime that doesn't make any sense. I guess it was fine, and some people like it, but to me it just really lacked in anything interesting or unique.
So, sorry for the tangent, but the short answer is (and I'm assuming you meant S2 and S3 in your question) - (a) good is probably the wrong word, but I definitely think S2 is worth a watch; S3 is very mid, and I guess mainly hinges on whether you can buy Mahershala as the protagonist; (b) no, nor anything else that made S1 special.