You should give it a chance. The worldbuilding worked for me, and LOTR is one of the few fandoms where I tend to avoid AUs and crossovers and such. And the whole Ungoliant backstory for Natasha was a bit of an unusual take on the spiders, but in the context of the story I could go with it. She is only a minor character here, but there are some nice interactions with Bucky and clearly more is implied with her and Clint, and she is important in several action scenes.