I guess it is. Possibaly because Leone is brilliant at montage, he'll gladly use 10 set ups where another director will only 3 or 4. In this case though, much of the action is covered in one continuous, though fluid, set up, with just a short series of mid shots and one close up following it.I've always been interested in Mo's relationship with the Latino guy who he hastily gives money to, too get rid of him. It's as though we are seeing the new gang on the block, who have come along and taken over from the old Jewish mob, just as they took over from Bugsy's (Irish?) gang. Noodles even notices a group of them gambling in the street in an earlier scene.
Another bit I liked was right before the gang executes Joe and his thugs at the dockyard. . . James Hayden's only real big scene in the movie. He walks over to Joe's car with a goofy grin on his face, looking like he's chewing on a wad of gum, looking for all the world like an innocent teenager/young man, and then - BLAM! He whips out his gun and blows Joe's eye out. Wow. But I agree with the other person on this thread who said it, this scene is the most definitely Leone one, with no music, natural sounds (the seagulls), lots of suspenseful build-up, and only a few brief lines of dialogue before an explosive climax.
That's one scene in the movie that seems to be very different than the rest of the movie.
Thinking about it since Delli Colli's death, there is an almost identical sequence in ONCE UPON A TIME IN THE WEST when Jill arrives at the station.