After last weeks "The Dirty Half Dozen" saw SHIELD attack a Hydra base in order to rescue Lincoln and Deathlok from SHIELD, "Scars" has Coulson attempt to set up a meeting with the Inhumans in Afterlife in order to make sure that they aren't a threat, while Gordon and Raina infiltrate Gonzales's ship in order to find out if one of Raina's visions was accurate.
It can't be easy being a penultimate episode in a serialised show like Agents of SHIELD - your main responsibility is to ensure that everything is ready for the season finale, whether that be getting characters in the places they need to be or ensuring that important events are set up properly, and in all fairness "Scars" performs admirably in that respect. The problem is that "Scars" has nothing else to do really - other than the big reveal of what Theta Protocol actually is (something that anyone who has seen Avengers: Age of Ultron should have already figured out) "Scars" has nothing to do that isn't simply working towards the finale.
As such, deciding if "Scars" is a good episode or not depends almost entirely on if the feature-length finale "S.O.S" ends up being worth the set up. One thing I will say for "Scars" is that it isn't predictable - there is a very obvious path leading to where Agents of SHIELD obviously wants to go for its finale, but "Scars" doesn't take it, instead choosing to perform something of a rug pull by setting up things exactly the way you would expect before a sudden twist completely re-contextualises certain characters. I realise that I'm being vague, but it'll be interesting to see how the finale deals with this turn of events, and it's nice to know that the writers of the show knew that the obvious way of causing the signposted conflict was just a little too predictable.
Regardless, "Scars" ends with one hell of a cliffhanger, teasing something that anyone worth their Marvel salt has been anticipating since Cal was first introduced to the series, while at the same time setting up everything that "S.O.S" seems to need in order for the season finale to really kick things up a notch. In a series that marks such a vast improvement over it's predecessor, Agents of SHIELD is going into "S.O.S" in the strongest position it has ever been in narratively, and I can say with some confidence that it will not disappoint.