Well, this is clearly the conclusion of the Chapter Black Arc & if I'm being honest and I hate saying this about two arcs in a row but it doesn't quite hold up to the same standard I once held it too. I think I can pin this one more on Hunter x Hunter as it surpassed Chapter Black in every way imaginable with Chimera Ant. Revisiting this after seeing Chimera Ant was like reading the first draft of a masterpiece, long before it reached that status. I'd also put some blame on the anime adaption, which in most regards just improved upon the source material (sole exception being the quick battle between Sensui/Yusuke when they went to capture Kuwabara).
That's not to say that it's a bad arc. Well, you could certainly argue that on the principles of the *terrible* resolution. The fact that Sensui was defeated only thanks to two Deus ex Machina in a row is something that always sullied this arc. But it still had it's positives & one needs to look no farther than the villain to see that. Sensui is easily the best of the main antagonists & Toguro was no slouch himself. Can hardly think of a more insane villain, especially in battle shonen (I'd argue there doesn't exist one for that category). But he wasn't just insane, he had his depth & the way the series parallel him with Yusuke was interesting. The general themes were still good & interesting yet feel under-developed in light of his more recent works (that's true of most aspects here really). All of Kurama's "fights", particularly Game Master, are among my favorite in the series especially in terms of unorthodox battles. I still really like this arc but the manga version at least, isn't as strong as I once thought. I'd go into more detail but I don't want to prattle on forever about this.
Instead, I throw a quick note that I like the fact that, at the end, the majority of the final chapter is dedicated to showing us what happens to the villains. Togashi writes the most compelling villains in battle shonen, easily & while I wouldn't throw Kamiya or Sniper as two of his best by any stretch, the fact that he focuses this time on them does show why that's a talent of his because more often than not, he doesn't just treat them as villains.