It's a "classic", at one time the classic, but I don't have much respect for an author who's glowing portrayals of the wonders of the Soviet economy were over the years quietly modified and then dropped as the truth became too well known to be ignored.
Agreed on both your points. (His college textbook is probably the thickest in my economics collection.) I lost a lot of respect for him over the Soviet era. It undermines his credibility on many other issues. Economics is already a soft science (compared to physics, etc.) so having trust in the authority of it's pole bearers is pretty critical.
Exhibit number N on why the neo-Keynesians don't get much respect today (well, not counting those they empower).
And it was worse than I'd remembered when I composed the above; as Wikipedia says, "In Samuelson's 1973 edition of his famous textbook, he laid forth the prediction that the Soviet Union would catch up to the United States in per capita income by 1990, and almost certainly would by 2015 because of its superior economic system. Subsequent editions of his textbook would later push the date of his prediction back farther until the Soviet Union ultimately collapsed."
