Well he does tell you that if you just absolutely need an ending then read on. But the end doesn't equal the story any more than sex equals the messy part at its conclusion. Obviously he wasn't satisfied with the ending, and who would be? By the time I got to the last book the Dark Tower had grown to such an object of mystery and power in my mind that I wondered how King could possibly do it justice in the end.
The simple truth was that he couldn't do it justice and he all but admitted as much. Even so, I think that the ending King wrote was as good as any despite the sort of Tales From the Cryptish aftertaste it gave me.
All in all the series gets a big :thumbsup: from me. It's the only series that has ever had me ravenous for the next book immediately after I finished the latest to come out.