I too was disappointed in the finale.
Some things I did like: Deke become less of the constant punch line on the show. And him finally saying what I've been saying: he survived an Apocalyptic hellscape yet gets no respect by anyone. IMO how they've written him, always as the joke, has always felt off for me.
Flint. He better be in the next season. But it highlighted what I didn't like about the episode and that was how they wrote Sarge's final turn. How come Mac and YoYo get to be so sure about how Flint is just Flint, yet give Daisy a hard time about Sarge not being Coulson? Oh, he's the devil that wears a familiar face, but the manifestation of their fear is just a kid they once knew? Which is why I think Sarge stabbing May to shove her in the portal should have been a fake-out, (as Izel suspected for a short while). That enough of Coulson was in that manifestation that was created to outwit the big bad, get May in a position to do the most good, but maybe at the end, he makes the sacrifice play and goes back into the other dimension to save the rest and close the portal, the ultimate Coulson move. Because Daisy and May arguing for two episodes about Sarge, then trusting him, just to have that ending just undermined all of that and made it all pointless.