These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Known Space
Idiot Plot: The plot of "Neutron Star" depends on pretty much every named character not expecting tidal forces around neutron stars, despite such forces being clearly understood in the 1960s, when the story was written.
Although "Neutron Star" was retconned later in Crashlander and Juggler of Worlds to be a limited perspective on a deeper Puppeteer/ARM game where the only person not truly aware of the tidal force was Beowulf. It's still' pretty dumb of a pilot not to know this.
It's the Same, Now It Sucks: There are two things preventing Fate of Worlds from being a satisfactory conclusion to the Ringworld series: Louis is mostly only a passive observer of events, just like he was in The Ringworld Throne, and the ending is essentially the same as that of Ringworld's Children in that it involves moving multiple-planet-sized objects through hyperspace to get away from attackers.
Jump the Shark: Ever since Carlos Wu's autodoc was introduced in "Procrustes", it became a MacGuffin that allows everybody who possesses it to solve all their problems with nanotechnology.
Justified in most cases, though. The Puppeteer "females" are actually a separate species that the puppeteers use to incubate fertilized eggs (in the same manner that predatory wasps will use a paralyzed caterpillar to incubate their eggs), and the Kzinti had selectively bred for non-sentient females for several thousand years using genetic technology they stole from a more advance race.
Also, this comes back to bite the Kzin in the ass on more than one occasion, when they underestimate both Kzin and human females. So...Fortunate Implications?
On the other hand, the Grog are a sentient alien species whose males are non-sentient.