It certainly is the most disturbing novel of King's that I've read. It's a good mixture of terror, horror, and revulsion (using King's definitions from Danse Macabre). For me, the most terrifying moment stems not from the loss of Gage, but the just-barely defined nature of the Wendigo. That is one of King's strong suites: providing just enough details about a monster to make it go bump in the night, and letting your imagination fill in the rest. I was genuinely on-edge during Louis' trips up to the Micmac burial ground, but I suppose it was "only a loon."