Oh, this was simply breathtaking! The depiction of the Underworld was so vivid and captivating, and felt fresh and new despite all the versions of it I've encountered in books.
Snape and Harry were just spot-on, characterisation-wise, but I also really appreciated the glimpses into Eilleen, Tobias and Albus Severus. The ending was everything I could hope for, and I wasn't sure which way it would go until the very end.