Honestly, I was a little underwhelmed by the ending of 'My Glory'. The novel builds up this incredibly tense, almost suffocating atmosphere around the protagonist's quest for vengeance, and the climax delivers on the confrontation. But the resolution felt too tidy, too sanitized for the morally grey world the author had established. It wraps up with a sense of societal justice being served and the main character finding a form of peace, which I guess qualifies as 'happy', but it rang hollow for me. It lacked the bitter, complicated aftertaste the premise promised. I wanted more ambiguity, maybe even a pyrrhic victory where the cost was clearer. The final chapters rush through the emotional fallout too quickly.
That said, I've seen tons of readers on forums who absolutely loved it, calling it cathartic and satisfying. So maybe my expectations were just skewed by the darker tone of the middle sections. If you go in looking for a story where the bad guys get their comeuppance and the protagonist can finally breathe, you'll probably be content. It's a definitive ending, no cliffhangers, which is something.