Well, if you want to know opinion of his contemporaries you should read what they have written. Also, the third volume has a preface by Engels that tries to deflect criticism of contemporary economists.

> You should try reading Das Kapital.

Well, maybe you should try re-reading it, because as far as I understand it, it doesn’t say anything close to that; though I am sure there is an interpretation that claims so as there are dozens of various contradictory Marx’s interpretations.