I won't say much because I don't want to spoil anything, so I'll simply say this:
Those calling this a new "incest" episode, or calling Beth a weak character... you're missing the point. This is Rick and Morty, it's supposed to make you feel awkward. (Drunken grandpa kidnaps grandson to blow up the world with a neutrino bomb and then collapses, first episode, hello?) And Beth is at the core of Rick's dynamics, if you don't get that by now, you haven't understood the show's family relationships approach yet.
This is sci-fi's moral dilemmas at it's best: like Splice (2009, which I loved) or Predestination (2015, which I guess it's OK) the possible repercussions of these types of interactions are quite complicated, even "sick and twisted".
The writing here is superb, and like other users said, I literally laughed out loud with this episode: it's like I watched this episode half of the time with my mouth covered with my hand in dismay, and the other half just bursting in laughter.
For me, one of the best episodes. So much character development, so much depth here and yet so hilariously (and awkwardly) fun.