So I'm one of those weirdos who actually liked the F91 movie. It had huge problems, but if viewed as a clipshow of a good series that never got to be made, you can get something out of it. And regardless of what you think of that movie, the Crossbone Gundam manga salvaged the setting and characters into a good series. After reading that, I became curious as to whether any of the other mange set during this period were as successful.
Sadly, Silhouette Formula 91 is just mediocre. Characterization and plot are minimized to make room for mobile suit combat and
discussions about mobile suit combat. And that combat is more often than not awkward and hard to follow. The manga tries adding a little more depth when the crew encounters Neo Zeon refugees living on an abandoned colony, but they don't really do a whole lot with that, either.
I wouldn't call this terrible, but it feels like Bandai wanted to make some model kits, so they assigned a premise to a manga author, who in turn did what he was assigned, but never had any passion for the project. It's not very good at what it does, but it doesn't fail in any interesting way. This has to be one of the most forgettable parts of the Gundam franchise.