Others here have touched on the idea that you have to put it in context as to what came before Pet Sounds, and what followed it to "get" the genius of the work, as is true with any great work of art.
Pet Sounds: Most Overrated Album of All Time?
Try as I might -- and I have tried very hard -- I just don't get the "genius" of this album. I know that George Martin said that Sgt Pepper would have never happened without Pet Sounds, but I don't think the two are even in the same league. What am I missing?