This is really hard to answer, and I nearly answered it privately, bc I don’t want to sow dissension in the fandom, it’s something ppl love to scream into the void about. But I see you’ve already started drawing some fanart for the fandom, so I want to encourage you to stay with us!
Some fans would tell you that #4 onwards in canon have certain characters being forgotten or mistreated by the author. I would say that there are storylines that are dark to the point that, even with my very high threshold for Crazy Shit, even I’ve had to close whatever one of these later books and just say, “omgz Aaaaaanne, whyyyy… We didn’t want this, nobody wanted this…”

If you’ve come looking for perfect cinnamon rolls, we only have one, Mojo, and he’s a dog 😉
I’ve heard that the books get worse and stuff and I wonder if I should read all of them or skip some or…?

So this depends on your definition of “worse.” They are a pile of dysfunctional hipster trash vampires, and several characters, but specifically the main character in the books, do some exceedingly problematic stuff, and, arguably, he is not condemned by the author in the text. There are fans who choose to disregard all the books from #4 onwards bc of that, and that’s totally fine.
Your headcanon is your own, and you do NOT have to accept all of canon, and you do NOT have to interpret canon the way any other fan interprets it. Don’t let another fan bully you into thinking their interpretation is the Only one.
PERSONALLY, and I know I’m not the only one who feels this way: back in the old days we called the later books #the Vampire Crackicles (spoilers in that tag) and enjoyed them for the silliness, bc there is plenty of humor still in the darkfic. And there are those, like me, who want to read darkfic, too. We want to go there in fiction, and explore what the consequences of even the most atrocious actions are. Can a character who’s committed X crime ever be redeemed? Redemption might not even be about forgiveness from the victim, but the effort of that character to strive to improve. That can be so cathartic for the reader, whether the character achieves it or not, the inspiration can come from the fact that they TRY and FAIL! repeatedly.
I always recommend that ppl give each of the books a chance, even the most cracky have some good stuff in them.
For the most part I think we’re a kinder fandom than others, since we suffered through our own fandom creator waging war on our fanfic and driving us underground for years.
And the fandom is pretty welcoming, but I’ve found it’s better if you know what happens in canon, and can talk about it with other fans, make fanworks about it, or whatev. Even to criticize.
Like any social media, though, your fandom experience is what you make of it, follow the #vampire chronicles tag, find some bloggers you like, and reach out!