As the title of this review states, series finales are either good, or terrible. As an "older" viewer, I have seen my share of series finales. I remember the finales of "M*A*S*H*". Not good. The Cheers finale, pretty good. A lot of times it depends on if the viewer is a big fan of the series or just sort of a middling fan. The big fans often think the series finales are great. Anyway, the Supergirl finale wasn't anything special. They brought in all the past cast members. That was nice. But that was pretty much the only thing good about it. As a guy who can identify a politically correct social statement, I can say this about the series; it tried very hard to put those statements in the series. They weren't hidden. The series finale had the grand finale of the series long-running, primary social statement; a same sex romantic relationship. This one ended in a marriage, complete with personally expressed vows spoken to soft music. I was perfectly okay with it but the whole ceremony took about 10 minutes, or about 8 minutes more than necessary. That can happen when there is a social statement to be expressed.
I find it hard to believe that I watched all but a few episodes. I never thought it was a great series but yet I kept returning. Finally, the curtain has dropped. I'm probably better off it has.