BE has the combo of elite writing, acting, characters and setting to do very special things. I have Breaking Bad 4th after the three you named just off of having told us a great story with defined characters and character arcs while most of the other great shows out now are still early into their runs. Boardwalk has a ton of potential to be 4th imo, and is already an epic show. It just lacks...soul, for want of a better word. Scenes like the ones between Capone and his deaf son stand out not just because of their brilliance but because of their rarity. It can still come off as just a show about gangsters killing each other with some great dialogue and period wardrobe/setting. I always had no problem with them killing off Jimmy, but they haven't given us another main character getting significant/consistent airtime that we can latch onto. I don't know if Nucky, despite being a great character, is that person the audience can latch onto.
That's my objective opinion on why in general the show might not be regarded as highly as some. Me personally, I love BE (loved last season too) and look forward to watching it every week. A lot gets packed into the hour it's on and I'm into highly detailed, complicated shows. I love the 20's setting, love the large cast of characters and multiple, simultaneous storylines, love the dialogue, and love the themes. But I realize this show isn't as accessible as others (just like Mad Men)
As for this episode, it's even more
than the first. My island brethren, Dr. Valentin Narcisse, might be getting avi treatment once BB is over