That first half hour was some of the most intense TV I've seen in ages. Wow!
Unfortunately the second part couldn't match the first half. It felt like the characters stopped being smart and started to sink into old horror movie tropes.
Other random thoughts on the episode:
1) The show gave new meaning to the schoolyard taunt, "Up your nose with a rubber hose."
2) When flower guy was killed and his wife ran over, screaming, my take is that it's because she was a cannibal and NotDad had just killed her perfectly compliant, lobotomized food source.
3) Margo's escape to the Russian classroom. They mentioned in Episode 1 that No End House had recently turned up in Russia, so this made sense.
4) Seth. Oh, Seth. What the hell are you? My theories are as follows:
a) He was a regular guy in the real world, but when he got to No End House, he met a fate similar to JT.
b) He's an actual human, not a memory, who's willingly working with No End House.
c) He's a cannibal who became a real boy.
Notice that not only does Seth not have much of a history, but that he couldn't even answer how old he was. "Twenty-something."
5) Speaking of JT and becoming a real boy, it's impressive that the show could make me feel sympathy for a character who was seen cheerfully burning a body in a firepit earlier in the episode.