You know I have to say, I actually liked this season a lot. I was extremely disappointed with season 2, because of the ways I felt it failed as an adaption, but given how much this thing was just completely its own thing, it's not really adapting anything from the games, I found it rather enjoyable.
I thought the writing was mostly pretty great, it's really bewildering to me that so many of you are attacking that aspect. I think the general consensus from critics is right in the money here. Some of the vampire stuff got a little bit ridiculously sexual... But honestly... Welcome to the last two hundred years of vampire fiction... Vampires are sexual by their nature
I liked the new characters, and while Isaac and especially Alucard's arcs felt kind of forced and unnecessary, they certainly had high points that I really enjoyed. The ending was a hard meh all around. I'll certainly give you that Ellis is not great at endings, and their were several weird wtf moments throughout, but not enough to detract from how good the rest was. I loved Saint Germaine and everything in the Trevor/Sypha arc, except the twist at the end with judge, that was just a twist for it's own sake.
Last thing I want to say is that this idea that the characters all end up in exactly the same place is a pretty ridiculous claim. I mean yes, Trevor and Sypha are still out on the road hunting monsters, but they are certainly not the optimistic happy goofs they were at the end of season 2, Alucard is sad and alone, but now he's becoming a brooding and honestly creepily weird, frightening vampire hermit. Much like a more benevolent version of Dracula from the original novel. Hector is captive, but now he's at least close to a respectable level in Carmilla war machine. Isaac has probably changed the least, but even he has gained greater sense of purpose and determination.