Pretty good
Considering it took me over a year to read the book, this mini series was so good. So what if some of the other supporting actors aren't quite as good as the main actors and the villain and it's bound to have some goofy moments (to be fair, other mini series based on Stephen King's work had lots of goofy moments, Langoliers included), but the translation from the book to the small screen was good even if other stuff were cut out, the acting was pretty good, some of the effects, while a tad dated, are decent enough for it's time back in 1994, the soundtrack fitted the atmosphere, and the cinematography is superb.
So is it one of the best Stephen King adaptations? Not quite. I think The Shining, Carrie, and Misery are my favorites (planning on reading The Green Mile and watching that adaptation in the future). But this is still a good mini series overall.