Well, the Power Rangers have fought their final battle. The forces of evil had teamed up against them, and the Rangers were outmanned, outgunned, and running out of time.
We now see why the forces of evil are so fixated on Earth: we're their last target. They have conquered the rest of the galaxy with very little oppostion. Other than the Earth's Rangers, the Aquitar Rangers, Trey (the Gold Ranger), the Phantom Ranger, and the Blue Sentinel, nobody remained to oppose the dark forces.
And they managed to defeat all of the above. Evil pinned down the Rangers' allies and overran the Earth.
In the conclusion of the countdown, the Rangers have few options. They still have their powers, but these are of little use; evil would just overpower them as it did before.
Astronema, however, offers an ultimatum. If the people of Earth don't hand over the Rangers, she'll destroy the planet.
Andros, against his friends' advice, sneaks aboard the Dark Fortress to confront Astronema, pleading with her, not good versus evil, but brother to sister.
Aboard the fortress, he finds Zordon, who informs Andros the forces of Evil have taken the rest of the universe. Zordon says that, by releasing his good energy, good will triumph but he himself will die. Andros cannot bring himself to do kill Zordon and continues to search for Astronema to talk with her.
Andros, however, has overestimated his powers of persuasion, and he gets into a fight against Astronema, in which he apparently kills her.
Ecliptor finds Astronema dead, and attempts to kill Andros, who releases Zordon, thereby destroying the evil.
Meanwhile, on Earth, everyone in Angel Grove claims to be a ranger, in order to protect the true rangers. The five on Earth, however, reveal themselves and fight the evil in Angel Grove, with the help of the people of the city
The goodness shockwave, however, flies through the universe, turning most of the evil to ashes. Zedd and Rita turn into normal people, Divatox turns into her true Inquirian self, and the Rangers powers disappear
Andros lands the Dark Fortress and brings out Astronema, who comes back to life as his sister, Karone.
The people of KO-35 move back into their planet. Andros, Zhane, and Korone at first appear to stay, but instead return to Earth with the other four.
I loved this episode. That's all there is to it. What, exactly, did I like?
And what didn't I like?
Questions for another day? Possibly.
Now that we have an ending point, we can look back and see the beginning point, and how much the show has changed over time. And it has. A show that used to be 'fight the monster each week' has become, well, good. Power Rangers in Space had the subplot of Andros looking for his sister, an initial Zhane vs. Andros (over Ashley), and had more talking and less fighting.
Power Rangers in Space (and the last season of PRT, for that matter) also foreshadowed, another good plot device IMHO. The keycards on the gangster planet, Astronema's necklace, and Darkonda's knowledge of Astronema all alluded to the Mega Voyager, Astronema's relation to Andros, and Darkonda's kidnapping of Karone, respectively. Power Rangers Turbo, with the Blue Sentinel's message of the alliance and the messenger's message to Dimetria that she as a sister also alluded to the alliance and Dimetria's relation to Divatox (in case you couldn't tell by the voices).
In conclusion, Power Rangers has made a considerable progression for the better.