Michael Parenti has been a widely acclaimed and popular political scientist, especially for the left.

His works such as Inventing Reality and face of imperialism have been positively received by academics and general population alike; his book "Democracy for the few" is a standard college graduate level textbook. Parenti is also a great public speaker, and knows how to win over an audience with charisma.

But one has to understand that Parenti is a political scientist, not an academic historian, so one has to critically read what he has to say about purely historical matters. His work, Blackshirts and Reds had some good insights but the section on the Soviet Union was imo on the weaker side and I would recommend other historical texts over it.

But all in all, Parenti is a relatively well known and political scientist and the books that you've mentioned in your questions, are quite good. Hope this answers your question.

I haven't read the other works but Democracy for the few was one of the recommended textbooks for our course, and it challenges student to critically asses the dominant pluralist paradigm. I've found favourable reviews by academics of the book. It was a quite an interesting read, even if I disagreed with the author on his interpretation on a couple of issues.