I thought this was very good. There's little to say that hasn't been said already but let me add one thing:

I've seen some reviewers say that that this isn't an ending, that's sequel bait or blah blah blah... I completely and absolutely disagree with that.

I'm going to get into spoiler territory so leave if you want to go unspoiled: We have three main characters with three personal objectives (rescue humans, get her powers back, take the king out respectively) that they *all* manage to accomplish, plot-points whose set up goes as far back as issue 1 (Lex Luthor's blood) have a pay-off and are closed-off, the main villain is defeated and one of the protagonists get irreparably changed. This is as much closure as you can have. The story *has* an ending and if they ever continue, it'll be a completely different story with different players.

What we don't have is a "nice" ending, it's bittersweet at best and, due to the actions of some characters the setting continues mostly unchanged. But that's also a point the story is making.