Like most political pamplets it overdoes the point and rambles in places, particularly about internal disagreements and squables that have lost all meaning. It is in essence a polemic against anarchism. Its key points are essential though:

—To end capitalism you must destroy the capitalist state.
—The state is an instrument of class rule. A way for one class to impose its rule upon another.
—Both communists and anarchists agree that the state must be destroyed.
—However, in learning from the Paris Commune, revolutionaries must seize and transform the state in order to be successful.
—During and after a revolution, reactionary forces will attempt to reverse the revolutionary process and the only way to stop this is to utilise the power of the state.
—The state will wither away within a socialist process, but to attempt to do this prior to revolution is to deny the possibility of revolution and to do this during/after the revolution is to open the door to its reversal.

Best quotes:

On the book remaining unfinished as a result of the October Revolution

"It is more pleasant and useful to go through the "experience of revolution" than to write about it."

On the nullification of radicals after their death (Mandela, Frida Kahlo, etc)

"During the lifetime of great revolutionaries, the oppressing classes constantly hounded them, received their theories with the most savage malice, the most furious hatred and the most unscrupulous campaigns of lies and slander. After their death, attempts are made to convert them into harmless icons, to canonize them, so to say, and to hallow their names to a certain extent for the “consolation” of the oppressed classes and with the object of duping the latter, while at the same time robbing the revolutionary theory of its substance, blunting its revolutionary edge and vulgarizing it."

On capitalist democracy

"Freedom in capitalist society always remains about the same as it was in the ancient Greek republics: freedom for the slaveowners."

"To decide once every few years which member of the ruling class is to repress and crush the people through parliament - such is the real essence of bourgeois parliamentarianism, not only in parliamentary-constitutional monarchies, but also in the most democratic republics."

Quoting Engels on the anarchist criticism of communists as 'authoritarian'

"All socialists are agreed that the state, and with it political authority, will disappear as a result of the coming social revolution, that is, that public functions will lose their political character and become mere administrative functions of watching over social interests. But the anti-authoritarians demand that the political state be abolished at one stroke, even before the social relations that gave both to it have been destroyed. They demand that the first act of the social revolution shall be the abolition of authority.

Have these gentlemen ever seen a revolution? A revolution is certainly the most authoritarian thing there is; it is an act whereby one part of the population imposes its will upon the other part by means of rifles, bayonets and cannon, all of which are highly authoritarian means. And the victorious party must maintain its rule by means of the terror which its arms inspire in the reactionaries. Would
the Paris Commune have lasted more than a day if it had not used the authority of the armed people against the bourgeoisie? Cannot we, on the contrary, blame it for having made too little use of that authority? Therefore, one of two things: either that anti-authoritarians don't know what they are talking about, in which case they are creating nothing but confusion. Or they do know, and in that case they are betraying the cause of the proletariat. In either case they serve only reaction."