This is a fine collection that provides readers a good overview and valuable introduction to various sources in Marxist political writings. 

That being said - I want to point out to readers that the more I read from the publishers Haymarket Books, the more I am leaning to the belief that they are Trots (or at least, are apologists for him). They have unfortunately excluded writings from Mao and Stalin here. From Le Blanc's own introduction, he states that while past handbooks to Marxism have usually included works from the Marx-Engels-Lenin-Stalin group of four, his own personal belief is that Stalin should not be included, and the foursome should be Marx-Engels-Lenin-Trotsky (lol). Make of that as you will, though I suppose reading Trotsky is good in a "know your enemies" kind of way. 

Aside from that, this is a valuable book. I used it as an introduction and to catch up with revolutionary viewpoints. I would recommend Losurdo's book on Stalin for further reading from here.