It's a mess.
It's just 3 episodes that were actually supposed to be 5 episodes and not need to serve as a sort of halfway series finale. And then while the scripting was underway the studio phoned up the writer and pretty much said "yeah, we're ending the show so you need to wrap things up in this and also cut it down almost in half."
So basically it's about 60 minutes of machine-gunning over a dozen new characters at the audience in a series of "hey, I'm <name> and I can do <thing>!" scenes where they get their exposure and are then never seen again. And somewhere in there is an excuse plot to send characters to another planet and introduce the Headmaster and Powermaster sub-lines of toys. And also Scorponok and Fortress Maximus.
Also by this point the budget had fallen off to the point that the show could no longer afford Toei as the primary studio (and also Toei likely pulled out of the running so they could concentrate on the unrelated* Japanese sequel series, Headmasters), so instead it's animated by AKOM at their AKOM-iest, which means that it's a flat, boring, flavorless mess from a visual standpoint.
*unrelated insofar as US season 4 doesn't count in Japan and instead they go right from the end of season 3 to Headmasters. But it features some of the same characters and Headmasters' first dozen or so episodes have enough similar story beats to The Rebirth that it's highly likely they cribbed that arc from a treatment of The Rebirth that was given to the Takara side of things before the decision to go in a different direction was made. I could go on at length about The Headmasters and its many many problems, but I won't unless someone really wants to know.