Let my start with this: Dawn of the Jedi: Into the Void by Tim Lebbon isn't a masterpiece; it's not the "greatest Star Wars novel ever“, and it's definitely not the book I would recommend people read if they are getting into the Expanded Universe for the first time.
All I want to do is quickly talk about some things the book does well - in my opinion - and why I do enjoy this novel more than your average Matt Wilkins.
Lets talk about the plot quick:
The book takes place 25.000 years before the films, and shortly before the comic series Dawn of the Jedi by John Ostrander and Jan Duursema (both can be read on their own though). The young Je'daii Ranger Lanoree Brock gets assigned to track down a fanatic cult leader, who tries to activate an ancient Gree Hypergate on Tython, which can be used to finally leave the Tython Sytsem and the Deep Core and explore the outside galaxy. The twist: the cult leader is none other than Lanoree Brock's brother, who was believed to have died. Lanoree travels through the Tython System searching for him, trying to stop his plans at any cost. Alright, that's the basic plot. I think it's a fine story with some fun aspects.
My favorite part about this book is, no doubt, the worldbuilding. One of my problems with the Dawn of the Jedi comics was the rushed opening; we get a massive Exposition dump right at the start, before being introduced to the main threat of the Rakatan Infinite Empire; so we basically had no real chance to see more of the Tython system and society during their „normal“ existence.
Into the Void already has the advantage of being able to show us this different time period before the galaxy-changing stuff happens in the comics. Instead of just telling us everything about the setting, the Je'daii, the Tho Yor and so on, it throws us into the plot immediately, and shows us those things; similar to A New Hope, which also didn't waste too much time with exposition and explaining every detail about the backstory. I enjoyed that aspect of the novel very much.
During the story we follow Lanoree through the Tython System, visiting different planets and landscapes, showing us this new setting for the Dawn of the Jedi era. Of course this also suffers from the fact that this good setting wasn't used more, because of the Disney buyout and the end of this era and the EU as a whole (the biggest problem Dawn of the Jedi has)
Similarly I also really liked the flashback portions of the book; basically almost half the book is flashback scenes to Lanoree and Dalien Brock's youth and training; again, I think Lebbon does a good job expanding the setting and world of this new time period. We get to see the journey the Je'daii have to go through to became Ranger's. They travel across the planet Tython and visit it's different Je'daii Temples, learning new aspect of the Force in each one.
This leads me to another thing I enjoy, which is the villain: Dalien Brock. Aside from the flashbacks he doesn't get much screen time in the present day storyline, but his backstory is interesting. He's someone born without any connection to the Force in a family of Force users that expect him to become a Je'daii like them. He starts hating the Force itself, wants to show that even as a normal man he can keep up the Je'daii powers. I really liked that take on a villain, and wish it could have been explored even more. But as is, Dalien Brock is a fine antagonist in my opinion.
Of course I can acknowledge that the book has it's problems(while I don't hate Lanoree Brock, she's definitely more on the Kerra Holt side than the Zayne Carrick side when it comes to characters); like I said, this ain't a masterpiece, but I do think it gets too much hate, especially when we have truly terrible books like Clone Wars: Gambit.
I for one would have been curious how the rest of this Trilogy would have played out, and of course I would have loved for the Dawn of the Jedi era to be expanded even further. At the end, we can all at least agree that this was an interesting new and fresh concept that didn't get the time to really shine.