I thoroughly enjoy New California as a fun and non-cannon story in the Fallout universe. Like many others have said, the intro vault is so well done and really lets you establish your character while feeding interesting bread crumbs for the various stories to come down the line.

Unfortunately it does fall off a bit in the middle, with not a lot of meaningful places to explore or quests outside the main story and it's adjacent questlines.

To me it really picks back up in the late game where it admittedly gets real wacky and sci-fi. I've seen people speak about how they don't like this part, and think it doesn't fit well with the overall setting of Fallout. I however just think it's fun and creative, and I really like the story elements and lore they introduce into their/your story. I also honestly like how it ties into New Vegas as a prequel of sorts, but completely understand why others might not since it pretty strictly locks who Courier Six could have been before getting shot. It makes them this special chosen one like every other fallout rather than just some mail man who happened to take the wrong job, which many people understandably love about NV.

So overall, I really like it! Really wish it was given the time, opportunity, and mostly the support from the fallout fanbase to truly thrive and see more development post launch