First, let me say that the Elvis renditions on trivia night were themselves worth the price of admission. Zoe Kravitz's "Don't" - one of my favorite Elvis songs anyway - was nonpareil. And Adam Scott's performance of "The Wonder of You" was nothing to sneer at, either. (Though my wife tells me he was lip-synching - well, kudos to the singer and the lip synching.)
But back to the plot: the ending was just right for this kind of whodunnit, because the "culprit" was the person who we would have least reason to even remotely suspect. Bonnie (played by Zoe Kravitz) had no reason to kill anybody.
Until she saw what Perry was doing. And, even then, she didn't intend to kill him.
But, boy, did he deserve to die. (Which is why I put "culprit" in quotes.) Not only because of what he had been doing to Celeste, but because he is revealed as Jane's rapist. That was a wild twist, and maybe the one weakness in the plot - wouldn't she have recognized Perry? However much he changed, his eyes, his voice would have been the same. But we do get the additional irony here that not only was Perry to father of violent Max, but of sweet Ziggy.
I'll conclude with saying I honestly don't know who should get the Emmy for best lead actress, Reese Witherspoon and Nicole Kidman were both so extraordinary in different ways. Reese Witherspoon walked the line between being a bitch and a caring woman just perfectly. And Nicole Kidman as an abused woman, trying to hold together her marriage, was indelible. As for acting, hats of to Alexander Skarsgard for an unforgettable performance as the despicable Perry.
I'd watch another season in a heartbeat. But this short season has already made television history.
See also Big Little Lies: Big Good, Truly ... Big Little Lies 1.5: Multivalent Whudunnit