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.
Esoteric Happy Ending: At least for thousands of people from Midkemia in Riftwar Saga, who ended being slaves of the Tsurani during the invasion. Is not stated what happened to them and by Pug POV (and the statement of Asayaga) they either ended in hellish conditions dying like animals or as a sex toys of the conquerors. You know, a happy alliance between worlds.
Later books (in particular The Empire Trilogy and the circumstances of Kevin leaving Mara's service) seem to indicate that a prisoner exchange and release of Midkemian slaves back to their homeworld followed.
Idiot Plot: A last-minute plan change in Shadow of a Dark Queen arises when Roo remarks that the Emerald Queen will need to build a new armada before she can send an army halfway around the world, and Calis and company decide to try destroying Novindus' biggest shipyard to put her back several years. Until Roo spoke up, nobody thought to ask where she would get ships of the size and number she would need to carry out her inevitable invasion.
Mary Sue Topia: The eledhel in Elvandar. They are all morally upstanding, all beautiful, all skilled. Their very home is a work of art, the mere sight of it sure to drive the most grizzled veteran to tears. They harbor no resentment for anyone, regardless of reason. Any elves who don't live as they do are considered unfortunate deviations from the ideal (as the term "The Returning" implies), but are generally happy to abandon their whole life's worth of teachings and values (and, in the case of the moredhel, family and friends too) and go live with the eledhel as soon as they realise how awesome they are. The glamredhel literally skip off to Elvandar as soon as they learn it exists. And of course, moredhel can go "good" and become eledhel, but no eledhel ever goes bad. Ever.
Note that there is ONE character in all the books who's been to Elvandar and has anything negative to say about it: Calis, Tomas and Aglaranna's son. He considers its static, unchanging ways to be "boring" and vastly prefers human company.
The Problem with Licensed Games: Avoided, as Betrayal at Krondor received critical acclaim and Feist liked it enough to novelize it personally. He even transported some of the game characters into his later books.
The Scrappy: Prince Patrick. He's an arrogant spoilt brat who rules over the Western Realm and is clearly unfit for the position to the point that no one really seems to like working for him and Pug can barely tolerate him.