The first episode is a summary of SM, SM R and SM S, the second episode is about Haruka and Michiru on a cruise ship. They fight one of the SuperS enemies and decide to leave this villain to the classical Sailor Team. (That's an explanation why the outer Sailor Team doesn't appear in this season.) In episode 3 Chibiusa uncovers one of her classmates as a monster and fights her with the Sailor Team in a vampire castle.
I was surprised to see there's anything Sailor Moon left on MAL that nobody has reviewed, so I thought I'd do a quick write-up. The long and short of it is that this is worth watching, especially if you happened to want to see more of Uranus and Neptune, but it's also skip-able and has no important plot points.
Originally airing after episode 4 of SuperS, this 1 hour TV special is broken into three 16 minute mini episodes. The first is a simple recap episode of the three seasons prior and you can essentially skip it, it has no new material besides Usagi and Luna's
The second however takes place early in the story of SuperS, shortly after the solar eclipse. It tells what Sailor Uranus and Neptune were up to during this arc (and tries to handwave away their absence from the rest of the season with a brief explanation). The plot itself is a typical Sailor Moon style monster-of-the-week story, but hey, we get to see Haruka and Michiru being their glorious gay selves for a whole 16 minutes and what more can you ask for, we get Haruka being a playboy and Michiru getting jealous, a bit of fluff, and some fight scenes. Perfect.
The third on the other hand is protagonized by Chibi Usa who has a vampire monster pretend to be a student at her school. It's purely forgettable filler, the highlight of the whole thing is Ami arguing against the science of using garlic to fight vampires, but nothing about it is particularly bad either (besides, like the rest of SuperS, having its screentime overwhelmingly dominated by Chibi Usa).
Really, I'd recommend everyone just watches the second of the three minisodes and calls it a day, unless you happen to *really* love Chibi Usa and desperately want to see more of her. If only because of the Haruka/Michiru focus I give this an overall 7/10.