I finished Catalyst.
I won't bother using spoilers because there's not much to spoil. I'm still not a fan of Luceno's writing - it often feels more like I'm reading a Wookieepedia article than a novel - but Catalyst wasn't awful.
It added some depth to Galen and Krennic, and also added history to Krennic and Tarkin's rivalry which was nice. But, I don't know, this book never really gripped me. Despite liking Galen and Lyra, I had to push myself to finish this one, which is never a good sign. A lot of the text I just found boring and unengaging. I couldn't have cared less about the completely forgettable sidestory about Has Obitt. There were little bits that made me sit up in my seat, but they generally didn't last long.
And as I said there is nothing really to discuss spoiler-wise. If you've seen Rogue One, the events in this book play out pretty much exactly as you expect them to.
As a side note, I found the description of Orson Krennic as a party animal in his college days pretty funny - probably unintentionally so. It's hard to imagine pretty much any Star Wars character at a frat party, much less Orson Krennic.
Where sky and water meet,
Where the waves grow sweet,
Doubt not, Reepicheep,
To find all you seek,
There is the utter east.