I struggled with it because I felt the characters were shallow.
They weren't as fleshed out as King's characters usually are.
I tend to get so engrossed by a story that you care about the world and the people that inhabit it, I found myself to be particularly unfussed if the main characters got mullered or not with CELL. That for me was where it fell down.
Exactly! Perfectly stated (same for me .. what MBJ said...)