The ending of your story is critical.
But what I mean by "the ending" doesn't mean just the end of the storyline.
I mean the feeling the ending leaves the reader with.
That feeling is critical.
How do you want your reader to feel after reading the final page of your book?
One thing that contributes to the feeling left by the ending is whether or not the reader is left with a memory of how the story evolved.
That is often accomplished by providing a connection to the beginning of the story, even at the end.
Does that make sense?
I'm going to offer up a personal example that may seem rather trite, but to me, it is a good example of reconnecting the reader to earlier parts of the story at the end and, thus, producing a satisfied feeling that encapsulates the story as a whole.
In my next novel (The Small Adventure of Popeye and Elvis), the two main characters discover boats made from Yoohoo cartons floating down a creek. Inside the boats are notes written on strips of paper and folded.
The boys excitedly open the notes:
This is repeated several times in the story (for the first few notes).
At the end of the book, one of the boys is sending a boat and a note down the creek.
My brilliant editor suggested that he fold it:
(She refers to that as a "refrain." I love that!)
Of course that's what I needed to do.
That simple addition took the reader back to the beginning of the story in a wonderful, satisfying circle.
That addition left the reader with a memory of the early part of the story and, thus, an "aura" of the story as a whole, not just the end.
So I suggest that you might consider if there is any way to "bookend" an element of your story - to bring back at the end something important from the beginning - to give the reader a reminder of the evolution of your story - to connect the beginning and the end to leave the reader "full".
Just a thought....