I’ll be honest, I’ve seen it twice already. Second showing, half the theater either groaned, laughed, or said “what?” when Rey was revealed to be a Palpatine.
A middle-aged woman sitting behind me literally gasped out loud during the same reveal when I watched it. Her two sons, both ten-ish, just sounded confused and muttered about it for a minute or so until they just went with.
Similarly someone laughed during the Holdo-maneuver first time I saw TLJ, yet someone yelled “whoah” the second time I saw it.
It’s always funny to see how differently people react in theatres. I have never seen anyone actually get up and leave though.