First of all, King's worst film is "Langoliers". Second, I did not notice these pointless chitchat scenes he speaks of. Some of the plot is a bit loose, but nothing is completely pointless. I furthermore do not recall any shots of knees, though if the knees belonged to the beautiful Madchen Amick I think this is forgivable. Mick Garris has made many a bad film, this is true. And "Sleepwalkers" is by no means a masterpiece. But I think to lay down such heavy scorn is misplaced and really ignores the "fun factor" of this picture.
Oddly enough, Howard Maxford, whom I almost never agree with, seems to get this one. He calls the film "silly but quite lively" and points out the "nifty effects" and "gag cameos" (Stephen King, Clive Barker, Joe Dante, Tobe Hooper and John Landis). And there you go -- recognition of the fun this film was and still is.
Ron Perlman ("Hellboy", "Pro-Life") plays a cop and doesn't get nearly enough screen time. Not sure what else to say about that. Clearly they did not foresee the star power in Perlman.