Update: Twenty-two chapters in and we've met the Nihil, who are being set up as a major antagonistic faction in The High Republic as a whole.
Good news, I already really like them as villains. For one thing, they are a completely different kind of threat than anything we've seen in the franchise thus far, with abilities and methods that make them unique when compared to mainstays like the Sith, the Empire, or the Hutts. I've seen one chapter of them at this point and I already have a good understanding of their organization while not having it be so fleshed out that there is no mystery. They have strengths and weaknesses that make sense and, at this point at least, resonate with both the heroes strength and weakness but also the larger themes of the High Republic.