Perhaps unsurprisingly, the enormous last book in Stephen King's Dark Tower septet resists summation.
Had you asked me at about halfway through, I would have said that it is approximately the most boring book in the world and would Stephen King just stop already. I even considered giving up on it, because King just can't shut up. Not only do we have to know every detail of what happens to Our Heroes, as they continue on their destructive journey to the heart of existence, we have to know the backstory of every single minor character they encounter.
Perhaps this is intentional. Perhaps that first half is King's version of Tolkien's Dead Marshes - they help us understand the interminable length of Roland's journey.
But it's dull.
The second half, though - after the battle of Algul Siento is done, and King has stopped being obsessed with his metafiction (and it is metafiction, and it is pretentious, whatever he may say in his snotty Afterword), and the Beams which hold the Tower up are saved - when Roland and his companions (no longer ka-tet, say true) continue on the final leg of their journey, to the Tower - this holds real power. The tunnels which lie under the Dogan, haunted by Lovecraftian terrors, are truly, majestically creepy. The Crimson King's terrible servants, and the vampiric Dandelo in the white lands of Empathica, and the vast and beautiful Can'Ka No Rey, the field of roses before the Tower itself - these are rendered with that real and apocalyptic magic that the first three books of the series captured so perfectly. And the ending? It is, more or less, pitch-perfect. With just a little more editing, this second half would have been up there with The Lord of the Rings.
There is tragedy here. And there is joy. And love and hate and pity. There are rhythms of true poetry and pathos woven just beneath the surface of this story. But they are almost fatally muffled by all that padding. And that may be the greatest tragedy of them all.