They're pretty good. Along with Tarkin and most of the Plagueis book they're my favorite of the new canon I've read, but I've not read a lot of it. Was audiobooking them as they came out until CoH came back and cut into my mindless puzzle game time 😀. The Thrawns are the only ones I've read since. They aren't as good as I remember the original Thrawn trilogy being but I've also not read that since I was a teen, so no idea about actual quality.