Read it and find out!
Marxist economist Michael Robert has reviewed the book>"Suffice it to say that, although Piketty repeats the title of Marx’s book, published exactly 150 years ago, he dismisses Marx’s analysis of capitalism based on the law of value and the tendency of the rate of profit to fall and adopts the mainstream theories of marginal productivity and/or market ‘imperfections’ like ‘rent-seeking’. This leads to the view that capitalism could be ‘reformed’ and inequality reduced by such measures as a global financial tax or progressive inheritance taxes or more recently a universal basic income (Piketty is now advising French socialist presidential candidate Hamon on this now)."
Roberts say that Capital in the 21st Century is more of a rejection of Marxism than an update of it. Here's some links to blogposts about the book. Read these and then decide if its worth your time.https://thenextrecession.wordpress.com/2019/10/18/capital-not-ideology/https://thenextrecession.wordpress.com/2017/02/19/inequality-after-150-years-of-capital/https://thenextrecession.wordpress.com/2014/04/28/reviewing-piketty-again/