>when I got to full length novel it never really grabbed me like the others had.

Same. It was good, but it didn't feel like a part of the story. The first four novella are all kind of connected and complete an overall story. You could probably stitch them together and call it a long novel. The novel just feels kind of "extra" as does the novella that comes after it.

The second one is my favorite in the series.
I don't know if you're reading vs audiobooks, but the narrator for the audiobooks is really good.