I just saw this movie last night, and I don't get why there are so many negative reviews up here. I thought it was well-filmed and well-acted, with the possible exception of whoever played Henry. I kept thinking he sounded like the doctor guy from the spoof "Airplane." ("Not war, water! Mr. Gray wants water! And don't call me Shirley!") Beav (Jason Lee, I think) was hilarious, though, despite his weird toothpick obsession. Morgan Freeman wasn't bad, I guess. He reminded me of an inept Hannibal Lecter with eyebrow toupees.
The movie/plot/character development was all interesting and true to the book. It really wasn't scary, more action/adventure, but I didn't mind and most viewers probably won't. I figure the reason most people watch or read horror anyway is because they like seeing people who are worse off than themselves, and this flick had that in spades. (Giant intestinal parasite, anyone? No? How about some evil Space Truffles or whatever the fungus thing was called?) Its high point was the relationships between the characters, something King has always been really good at portraying.
Anyway, this movie was fun and good for a Friday night. I'd recommend it. Enjoy!