Before I start, a disclaimer: I had not read the books before watching the show, but I started reading the first book after the 6th episode and finished it an hour ago.
First, let's get the good part out of the way - visually the show is beautiful.
That's it.
The book series has been accused of not developing its characters properly, but the book is not about characters or protagonists, it's about the foundation itself. The show tries to flesh out characters(and fails), but that is inherently antithetical to the books because they are about mobs and society and their collective behavior. The show just tries to be a poor copy of Star Wars.
The show gives us an antagonist(or three) and tries to simplify the problems of the empire. It doesn't show that the cause of the fall is sheer entropy itself.
Also the pacing and writing in general is not very well done.