The anime wraps up at the end of 'Zuishin' Juemon's arc, which is around chapter 60 of the manga. Honestly, it felt like a decent stopping point even if it wasn't a full adaptation—they ended with Gabimaru and Sagiri finally reaching the island's inner layers and getting a clearer picture of the bigger threat. They resolved that major antagonist's story and gave the main pair a moment to solidify their partnership.
Watching it week-to-week, I was worried they'd rush or leave us on a total cliffhanger, but the finale had a sense of closure. Of course, it's just the beginning of the real craziness. If you're hungry for more, you've got to pick up the manga from around chapter 61; that's where the lore and the fights get truly unhinged. I jumped right in after the last episode aired.