I watched season 1 on DVD from Netflix. I liked it, but until reading this thread with so many of you folks praising it, I was ashamed to admit it. The biggest discrepancy for me was that with all those escaped prisoners plotting to destroy the world, Superman stays out of it, apparently because he is ethically opposed to helping the government. But I figured that either the makers of this series didn't have the rights to use Superman, or else they just didn't want to eclipse Supergirl: This is her story, not his. So I let it pass. I like that she is both humble and assertive. Vulnerable and strong. And of course it doesn't hurt that she is hot.
James Olson's metamorphosis from scrawny cub to strong hunk also grates, but I accept that also, because Supergirl needs a better love interest than the geeky guy.
I found a preview of episode 1 of season 2, in which the pod is opened and there's another Kryptonian. I said to myself, "Another Superman, after all the inconsistency we swallowed in order to keep the first Superman out of Supergirl's story???" And I decided not to bother renting season 2. (When it becomes available.)