Oh, man, Oy's death...damn, that has to be worst moment in all of the books for me. I don't mind people dying so much (although most of the deaths -- expect for the bad guys of course! -- were traumatic (King really has a way of writing those damned scenes, in any of his books, that really wring out the sadness)) but that little raccoon/dog creature I loved and I knew he was going to die and was dreading the moment!
I don't think I could have coped with the book ending like that, with the door shutting behind him and never knowing what was in the Tower...since we, the Constant Reader, have journeyed along with Roland, we too were
desperate to know what was in that Tower (ooh, a thought...perhaps the ending was King's way of saying that, like Roland, we had to learn that it wasn't the Tower that was important but the journey!
) and if the door had just shut and then it had ended, I think even I would've had something to say about it!
I read The Cat Who Walks Through Walls the other day and that had an ending that would be similar to that scenario and although, yes, it was left to the reader to make up their own minds, I still wasn't entirely pleased by how cliff-hanger-y it was!