While the effects in "Langoliers" are not the greatest, they are not the worst effects ever. Discounting the Doctor Who episode I mentioned in a similar thread (see
http://www.badmovies.org/bbs2/read.php?f=2&i=15327&t=15314 if you're curious), there is always "Gargantua," a TV movie made around the time of the "Godzilla" remake. It's special effects are remarkably bad.
Moving from TV Land, there is always "Howling: New Moon Rising," specifically the last werewolf transformation sequence. I could do better, and I've never done anything like it in my life. Its no threat to Jack "Wolf Man" Pierce's work, let alone any modern make-up man, and Pierce did his best work in the thirties/forties.
As for it being a dumb idea to adapt "Langoliers," I have to disagree. While it is not one of King's better works (Ted Sturgeon tells a similar, and better, story with "Yesterday Was Monday"), it is far from his worst. Not all movies can be action movies, nor should they be.
Of course, I won't argue that a little LESS talking would've been nice in "Langoliers" miniseries...