I'm not surprised some have a problem with the episode but I'm among those who loved it. I love holy-####-moments. They're tricky, especially in television shows. A lot of goes into setting them up and executing them, and appreciating them is subjective. I suppose there isn't much point in debating if the shocking scenes worked.
I don't think Boardwalk gets enough credit for atmosphere and mood. The way episodes unravel and flow into their final scenes is often subtly masterful and taken for granted. The flashback scenes with Jimmy were well-done, they sort of sneakily materialized into the present. I haven't seen it mentioned anywhere--but Jimmy snorted the heroin, correct? His in-and-out periods of consciousness, from the drugs and later from his wound, made the episode even more surreal. He existed in a new world; the old one was destroyed, and he couldn't find his bearing in it.
I thought the entirety of Jimmy as a human being was put on display and by the end he was completely devoid of what he had been. His gaze towards Richard as he cleaned up the mess was interesting. They're ships without a harbor now.
Buscemi has been solid lately. His scenes with Margaret were good. She's acting like a childish idiot so his exasperation that melded into "don't even think about ####ing with me" anger was warranted. Thought he pulled it off. Other than Richard I'm rooting for Nucky the most right now.
I've loved the subtle touches in the show, including, as you say, the mood and atmosphere, and also the pacing. Which is why I found the episode so off-putting. They tried to get too many things through the door, imo. Almost like it was written as a hail mary in response to the threat of HBO not renewing. But whatever, I'm not going to get bothered by it. The Commodore thing was ridiculous, but they needed to kill him off. So he's gone. We move forward. I also laughed out loud at the train during the incest scene, which was cheesy. What you mention was my biggest issue with the epsidoe...the subtlety. It seemed lacking, but so be it. One other thing...I don't buy Jimmy just leaving the Manny thing in the wind for somebody else to maybe or maybe not handle. He knows as well as anybody what a blood-thirsty lunatic Manny is and that he gets off on killing anybody he perceives as slighting him. There were two plays there only. Pay him or kill him. Jimmy's a terrible leader, but he's not an idiot. That was hard to swallow, too. But I digress.And yeah, Jimmy snorted the heroin. Looked like all of it, too, which from what I understand about heroin, would make him so ill that he'd probably not want to do it again. It'll be interesting to see where they go with that.