Ah, prequels. Showing how characters we already know and love before we ever knew them. While the previous Thrawn books talk about Thrawn’s past, here is where we actually see it. Parts of this book also take place at the same time as Alliances (in the previous trilogy), fleshing out further details of that particular Clone Wars adventure. And this book does assume you’ve read the previous trilogy. It pretty freely uses names of technical concepts with no explanation because those topics were covered in the previous books. I wouldn’t call it impossible to read Chaos Rising first, but you’ll get more out of it if you read everything in publication order.
Now, something I normally hate about prequels is that they take away suspense. Because other stories are chronologically later, you know certain characters can’t be killed. But here, it’s a very limited number of people. Thrawn’s been in a fair amount of media since his reintroduction to the canon, but the Chiss in general haven’t. So, most of the characters are fair game as this story unfolds.
The other thing that bugs me about prequels is reversing character development. In military matters, Thrawn is still the chessmaster he’s always been. But his slowly developing understanding of politics goes back to being non-existent. When he analyzes a situation, it’s from a purely military perspective unless someone else points something political out to him. While this does annoy me slightly, it’s also clever because it gives a near-unstoppable character like Thrawn a flaw that can be exploited on the basis that he’s still young and inexperienced in this area.
He also seems more compassionate in his youth. I attribute at least part of this to the fact that he’s still a captain. He can keep casualties light in a way that an admiral commanding more people (including pilots in easily-shot-down fighters) cannot. But we know from the future books that that’s where he ends up. And it’s so much fun to see just how he got there.