Favorite Underrated Parts of the Series

I am currently on my second trip to the tower (first through audiobook, physical books this time). I don't know if it's because I'm physically reading the books this time, but I'm gaining an entirely new appreciation for the series.

I just cracked open The Waste Lands this morning. I was awestruck by the entire Shardik sequence. His introduction is one of the most interesting and thought provoking things I have read. The way King wrote it just sinks it's claws into you (pun very much intended). Something about a 70 foot tall, insane, dying robot bear wandering through a forest, mowing down trees is fascinating.

So, what are your favorite underrated parts of the series? Whether it's the way King articulated it, the feeling it gives, the way it itched your brain, or whatever other reason you might have.