Short answer: A game and a book are far more different than movie/TV and a book. I thought the book was far better.
Longer answer
We have both. My daughter got further in the game which is a mismatched mix of adventure and combat. I found it unplayable.
I think the book was OK, but ages since I've read it. I've two versions of Magician on paper (allegedly publisher cut and writer's edit) and one that was on offer on ebook (the writer's edit version), that mysteriously was updated 3 times on Amazon.
Feist seems to find his own voice and more original story about halfway through Magician, so worth sticking at it even if you find the first 3rd a bit too stereotypical.
I've not all the Riftwar (or associated Janny Wurts titles), but plenty.
Edit:
It's on UK/Ireland Amazon for 99p, but not by edit link.
https://www.amazon.co.uk/gp/product/B0041RRCSG/
So I got it in case I want to re-read it. Easier on the Kobo Sage than on paper. I think the game title is Betrayal at Krondor.
Edit 2:
Stupid Amazon puts a "
:" in the download filename, which breaks backups! Does Windows even allow such file names? I'm running Linux, which does.