Seemingly razor sharp analysis of the constituencies in post 1848 German politics, with very careful attention paid to common and contradictory interests; of course I’m too ignorant to say if any of this was true, but it all seems very plausible. And a lot of it rings true for contemporary American politics, with the democrats using the state to bribe workers while protecting property at all costs. But now they don’t really even pay lip service to workers or socialism, they’re explicitly pandering to the petty-bourgeoisie–the much celebrated American middle class.
The strategy–support the petty-bourgeois faction against the liberals, but oppose their property-preserving measures in favor of direct worker control–follows clearly from the analysis. This is a nice appendix to the communist manifesto insofar as it fills in lots of details, the most important being worker armies, worker candidates, worker councils, state appropriation of private property (and apparently even communal property??), and state centralization. The problems with this approach are obvious to a 21st century reader, but I think I would have to read some anarchists to get a sense of contemporary criticism from the left. I also suspect a classical republican criticism would be pretty convincing.
This is furthermore a nice complement to the manifesto because the closing note is stronger: “Their battle cry must be: The Revolution in Permanence!” If Marxism still means something besides social democracy it would be this.