I was coming in here to say the ending sucked but phat and geek beat me to it in a much more articulate manner.
Geek,Click to see Spoiler:great observation as to why the ending was so emotionally unsatisfying, I agree with your synopsis. I'd rather he got it wrong and tried than for him to just end the book so abruptly. It would still have been a let down but my curiosity would've been satisfied.
phat -Click to see Spoiler:yeah, I caught the Charlie the Choo Choo mention, although at this point it seems to be a given that he includes fragments of other characters in all his books, as a kind of pop culture parody of himself. It's very smart marketing because the reader keeps reading to find out additional bits of information about the characters even after their book has ended.
It did suffer muchly in comparison to The Stand, but then I don't think he'll ever write anything else so compelling as The Stand or the Dark Tower series. I'm just fangirly about those books.