Nope, was too young when it came out, but I have this vague memories of slips of scenes I snatched here or there

You should watch it after you've read the book. It condenses the events described in the book somewhat (e.g., the course of the four trials is winnnowed down to a single one), but it renders the atmosphere against which the whole events took place very vividly ... and several of the actual people featured in the story (including, most notably, the Lady Chablis) are included in the cast.

I certainly will. I actually ear-marked this book long ago because the movie had so much atmosphere, and Spacey was so unnerving to my kid self.