Having seen a lot of book adaptations (coz sometimes original stories run out?) and a lot of times been disappointed in them (looking at you Harry Potter #4, the first one ever to disappoint me), I've learned to treat the adaptation and the book as separate stories. This adaptation is unique for me because I see the drama as the story on Tantai Jin's POV, while the webnovel is the story on Li Susu's POV. The two complement each other, and the things that the drama lacks, the novel supplies, and vice versa. There really are a lot of things to be wished for in the drama, but then that's why the novel exists.
Like the tower scene. I liked the drama's take better than the one in the novel, because it gave the characters a lot of things to talk about, explain, and feel. The novel was more devastating though, because Susu just... jumped. She never knew that Tantai Jin tried to catch her, tried to save her, futile though it was. She died believing that he loved Ye Bingchang, and had to carry that sadness all throughout the time she woke up in the immortal realm. LYX got Tantai Jin's derangement after she died spot on, though of course the novel took it further in that (TRIGGER WARNING: SUICIDAL ATTEMPT) it was implied even that he cut his wrists repeatedly in an attempt to kill himself even before he went to the Nether River. He failed because YXW's divine essence prevented him to die. (not to mention of course that he lay side by side with a decaying corpse... that was too morbid to imagine) (In addition, we were robbed of a silver-haired LYX! he looked so good in that color haha)
Definitely the end of the drama was something to be desired, but again, that's why the novel exists. But taking the drama as a whole, I think it told a complete story already, even if it ended with TTJ's death. Because that's the way life really is.... our story ends with our deaths, and hopefully we have left a legacy enough to have others take our story beyond our death.
(okay, I'm just saying this so I can cope with that ending, teehee. I join others in the misery of having such an open ended ending. I have rotten luck at picking Chinese dramas that never end satisfyingly.)