This isn’t going to be a long review because you are probably already familiar with these characters and this author from reading the much superior Riyria Revelations. If you want to spend more time with Royce and Hardian, then Chronicles will scratch that itch in at least satisfactory way.
The first book is better in that regard since it details the events leading up to the union of this unlikely pair. Which means it has a lot of Hadrian and Royce in it. Royce I find grating in this book. By the time Revelations rolls around Gwen and Hadrian have softened Royce. Here he is an unmitigated murdered with an extremely anti-social attitude. Mostly you are repulsed at his casual disregard for life and you wonder how Hadrian could ever team up with him. Sullivan doesn’t manage to salvage and answer to the last one from his singularly unpleasant depiction of Royce. Hadrian though pulls out some moves and while his constant reference to his dark past is a bit overdone, his essential good nature shines through. He really is a knight in shining armor, even later on. I, for one, am glad Royce never really corrupts him.
I also enjoy that it chronicles one of their great heists that is mentioned in passing in Revelations. That was the promise of these books, to see Riyria before the epic events of Revelations when they were just the fantasy equivalent of a fixer. The second book is not like that at all. It instead focuses mainly on secondary characters and leaves Hadrian in particular a bit player in his own book. So the problem is mostly with the plot than the writing. Sullivan still has a breezy style perfectly suited for the adventuresome duo of Hadrian and Royce.
Read the first, skip the second.