Struggling through Mary Shelley’s “Last Man”

Oh Mary Shelley… Why did you think the Last Man was your best work? It’s the slowest moving book I have read in ages.
Raymond is irritating, Idris and Lionel are inaccessible and Perdita just feels like a personification of how Mary Shelley and the other women around her felt, and what they could be reduced to when exposed to the whims of the romantic poets.
As for the hero worship of Percy through Adrian, Mary certainly lays it on pretty thick.
It’s certainly not a bad book, but I’m struggling to see why the author was more proud of it than her other works.
I feel like if I can understand that then the rest of this will be a piece of cake.
If anyone has any clues about how to approach this one I would love to hear from you!