In general, I like Dan Simmons very much, since I vastly enjoyed his vast and also monstrous Hyperion and the Fall of Hyperion sequel. I like very much that he took a favorite subject of mine-- the search for the "non-existent" Northwest Passage-- and melded history, mythology, horror and unutterable cold into it. I'm also quite sure that he took this novel too far.
I would have preferred less of a complete, point-to-point historical retelling of Sir John Franklin's final journey. Every step the doomed leaders took on this voyage is re-told in excruciating detail such that you cannot escape getting the feel for what such a journey would have felt like, but you also tend to lose the point of the entire exercise along the way. This does mean that when Simmons is ready to surprise you, what he writes shocks you entirely out of your stupor. But those moments are just too few and far between.
The ending also threw me for a loop. Or rather, kicked me right out of the story. It's an odd thing to have one particular theme for 94% of the book and then change that focus for the final 6%. It's off-putting, and unfortunately, it's also dull. I understand what Simmons was doing, but it doesn't make the final chapters more palatable.