The scare zones, particularly in Ghost Town are legendary. Those scareactors are incredible.
It's refreshing to see non-IP, original mazes... and for the most part, all the props are handmade specific from the park, so it all feels very unique.
If you've never gone before, I'd recommend the BOO-fet. You get the famous Knott's Chicken (all you can eat), scare actors roam around, and you get into many mazes 30 min early. And don't miss the large haunt store! Before Haunt, you can access it from the Marketplace, but you can also access it during the haunt through a back entrance they open up during the event. Not quite sure what time they close it, though.
Keep in mind this year, none of the rides are haunt themed, so you can save a lot of time by skipping them and just focusing on the mazes. You'll want to do many of them multiple times!