I really don’t get the adulation for that trilogy. While some of the stuff with Thrawn himself was good, the rest of it (a heart-of-gold-smuggler, a conveniently-secret fleet of ships and “Luuke” clones) was painfully mediocre.
Because it was great for the time period when the franchise was seriously sputtering out and revived a lot of interest in things.
The whole mole hunt thing was typical thriller novel stuff from the time but remember what was there before it.
A lot of it is the time frame. Prior to the Thrawn series media tie-in books were almost universally crap, and weren’t canon. They were basically cash grabs, throwaway junk for folks who wanted more than the movie/TV studio was providing. Then suddenly with Heir series SW changed the game, they hired a really good writer, gave him access to the bible, and let him do (sort of) whatever he wanted, and let it count and be considered part of the story told in the movies. And yeah some of it was rough, though a lot of that came from George (Tim’s got a long list of “stuff I wanted to do but George said ‘no’ that are actually really cool), and some were added later (now that we know they’re Sith “Dark Jedi” scans wrong, and clones weren’t so bad before the prequel trilogy). But for the time period it was head and shoulders above anything being done in the media tie-in world. Those 3 books changed the entire industry for the better. Any time you read a media tie-in book now that’s actually good that’s because of the Heir trilogy.