A prequel that has no connection to the other Maze Runner books apart from a slapped on first and last chapter? It's an odd choice for a prequel, but this was a lot better than "The Death Cure".
However, the characters are still quite cardboard and two dimensional, and the relentless racing from one place to another is exhausting rather than exhilarating.
The technique of having the main character dream his flashbacks wasn't needed either - the change of chapter would have done it, although the change of tense was a nice idea. I found the pacing of the flashbacks better than the endless running and fighting going on in the rest of the book.
In the closing chapters of the book do we get to feel some empathy for the characters when they discover they all have The Flare. How they fight or succumb to it gives them some depth, and the ending (although very rushed) is more powerful for it.