That's certainly an opinion... Quite a lot of condemnation for no real argument. I personally think surplus value and socially necessary labor time are quite straightforward, intuitive concepts. Meanwhile, I found this tidbit on Henry George's wikipedia page: "Upon Marx's death, George admitted he has not read any of his works, which were untranslated into English at the time,"

For anyone interested in reading more from Marx's side, Wage Labour And Capital by Marx is a pamphlet meant for mass distribution and not a difficult read. I've heard A People's Guide To Capitalism recommended as a high quality modernized version of the same ideas.