I thought the answer to that question might interest you.
I have just finished (edits and all) my novel, THREE SPIRIT KNIGHT and its ending was important to me.
An inept ending can kill your otherwise great book. So what questions do you need to ask about your ending?
1. Does it resolve the core conflict of the novel?
This is the big "this is what my book is about" question that your protagonist has spent the entire book trying to achieve.
This is a biggie for series books, as there's a larger story arc across multiple books. But the goal in that one book needs to be resolved.
2. Does it satisfy the major questions posed in the novel?
You don't have to tie up all the loose ends, but there are probably a few major things in the story readers will want to know answers to.
3. Is this the ending most readers are hoping for?
We've all read books where we wanted one ending, but the book ended another way. Let down the reader, and you can bet she or he will not recommend your book.
4. Is your last line memorable, summing up your entire novel?
The trick of a good ending, of course, is that it must capture and equal everything that has gone before.
The line “He loved Big Brother” (from a novel that ends as masterfully as it begins) means very little until you understand exactly who Big Brother is.
A great last line will have your reader putting down the book on her lap, murmuring, "Wow." Guess what book she next recommends to her friends?
5. A bad ending will unfailingly kill a good story. Is your ending such a one?
The ending is why the reader just invested their valuable time reading your story, and if it stinks, then they've wasted that time
6. Is there CHANGE at the end?
What makes a good ending hinges on the same things that make a good story. And the most important thing that makes a good story is change.
If nothing changes, nothing happens. And if nothing happens, you've got no story.
7. Do your characters save themselves or at least those they love?
If the U.S.S. Enterprise sails over the horizon to zap the bad guys in the nick of time. Say good-bye to repeat readers.
8. Resonance is the new Closure. Does your ending have it?
One symbol, or moment, from the beginning of the story is repeated at the end. By the time the story is done it means something else completely.
The ending echoes the beginning. It gives a sense that the story has come full circle.
9. Does it establish a new normal?
The heroes begin a new life. Sometimes the farm boy returns to the farm. Sometimes the farm boy becomes king. Sometimes the hero decides to set out on a new journey.
It's a chance to show how the character has been altered by the journey, and what they're going to do with that new knowledge.
10. What are your favorite kind of endings?
The best endings leave me full, and remain with me for days.
The best books make me wish they never end, but I know they have to. Which is why I enjoy series books.
That's the sort of ending I like. What about you?