Good
TNG numbered:
- #3: The Children of Hamlin by Carmen Carter - creepy but interesting, with cool sf concepts
But also written before the series premiered, so its take on the TNG era is pretty... alternate... compared to what we got. Its 24th-century Starfleet seems somewhat more aggressive, and there are some other discrepancies here and there. I tend to assume it's in an alternate timeline where the pivotal historical event that drives the novel's narrative caused the Federation to adopt a more militaristic mindset.
#4: Survivors by Jean Lorrah - strong backstory for Tasha Yar, good role for Data too
Another good one that doesn't quite fit with later continuity. Its version of Tasha's homeworld is tricky to reconcile with "Legacy," though not impossible; maybe New Paris was the name of the main colony on Turkana IV, say. But the bigger discrepancy is in its portrayal of Data. TNG didn't explicitly establish Data as emotionless until the start of the third season, in "The Ensigns of Command." Originally, the intention was that he did have the potential for emotion, just in an underdeveloped and subtle way, and that's the assumption that drives his characterization in both
Survivors and its sequel
Metamorphosis. Both books were consistent with canon at the time they came out, but overwritten by the retcons about Data's emotionlessness. (Which I never liked -- the idea that AIs can't have emotion was already a hackneyed sci-fi cliche at the time, and it makes no sense anyway, since emotion is a far simpler mental process than conscious thought and thus would be much easier to program.)
8: The Captains' Honor by David and Daniel Dvorkin - Picard meets a Starfleet vessel staffed by inhabitants of "Bread and Circuses"'s Roman planet
Now, that one was just weird, and contradicts TOS. In B&C, the planet was explicitly physically distinct from Earth -- it had similar conditions, but had differently shaped land masses and was the fourth planet of its star instead of the third. Bizarrely, the Dvorkins make it a "Miri"-like exact duplicate of Earth, with a precisely parallel history up until Sejanus's coup against Tiberius -- which is an in-joke, because Patrick Stewart played Sejanus in
I, Claudius. I also thought it was really implausible that a planet that was at a 20th-century tech level and still had slavery and tyranny in the 2260s would be advanced enough to be a Federation member in the 2360s. The contrivances necessary to make the story happen never worked for me.