The greatest modern historians of the French Revolution, from Albert Mathiez, Georges Lefebvre, George Rudé, to Albert Soboul, all on the Left, thought well of Maximilien Robespierre* and his fellow Jacobins.
Rare were anti-Jacobins among historians on the Left, till the post-modern reaction against the Jacobins, the reaction which Alain Badiou and Slavoj Zizek among others have sought to counter:
Robespierre serves perfectly today's anti-totalitarian
liberals who no longer need to portray him as a cruel
monster with a sneering evil smile, as it was the case
by the 19th century reactionaries: everyone is ready
to recognize his moral integrity and full devotion to the
revolutionary Cause, since his very purity is the problem,
the cause of all trouble, as is signalled by the title of the
last biography of Robespierre, Ruth Scurr's Fatal Purity. . . .
Happy us who live under cynical public-opinion
manipulators, not under the sincere Muslim fundamentalists
ready to fully engage themselves in their projects . . . what
better proof of the ethico-political misery of our epoch
whose ultimate mobilizing motif is the mistrust of virtue!
Should we not affirm against such opportunist realism
the simple faith in the eternal Idea of freedom which persists
through all defeats, without which, as it was clear to
Robespierre, a revolution "is just a noisy crime that destroys
another crime," the faith most poignantly expressed in
Robespierre's very last speech on the 8 Thermidor 1994,
the day before his arrest and execution:
But there do exist, I can assure you, souls that are
feeling and pure; it exists, that tender, imperious
and irresistible passion, the torment and delight of
magnanimous hearts; that deep horror of tyranny,
that compassionate zeal for the oppressed, that sacred
love for the homeland, that even more sublime and
holy love for humanity, without which a great revolution
is just a noisy crime that destroys another crime; it does
exist, that generous ambition to establish here on earth
the world's first Republic.
("Robespierre or the 'Divine Violence' of Terror,"
<http://www.lacan.com/zizrobes.htm>)
As for Karl Marx himself, he apparently did not know what exactly to think of the Terror, says Michael Löwy in "'The Poetry of the Past': Marx and the French Revolution" (New Left Review I.177, September-October 1989, pp. 115-116):
If Marx's analysis of the bourgeois character of the
revolution is remarkably clear and coherent, the same
cannot be said of his attempts to interpret Jacobinism
and the Terror of 1793. Confronted with the mystery of
Jacobinism, Marx hesitates. This hesitation is visible in
the variations from one period to another, from one text
to another, and sometimes within the same document.
Not all the hypotheses he advances are of the same
interest. Some of them, which are quite extreme -- and,
moreover, mutually contradictory -- are not particularly
convincing. For example, in a passage in The German
Ideology, he presents the Terror as the implementation
of the 'vigorous liberalism of the bourgeoisie'! A few pages
earlier, however, Robespierre and Saint-Just are defined
as the 'real representatives of revolutionary power, i.e. of
the class which alone was truly revolutionary, the
"innumerable" mass'.
In all the contradictory statements about the Terror that Marx made, Löwy detects three notable lines of thinking which Marx failed or refused to make coherent: (1) "The Terror is a moment in which the political becomes autonomous and then comes into violent conflict with bourgeois society," elaborated in The Jewish Question (1844); (2) "The men of the Terror -- 'Robespierre, Saint-Just and their party' -- were victims of an illusion," seeking to sacrifice bourgeois society to the republican ideals inspired by "an ancient mode of political life," a theme developed in The Holy Family (1845), which gets reinterpreted in The Eighteenth Brumaire of Louis Napoleon (1852), the illusion in question now represented as the ruse of reason, a necessary illusion; and (3) "The Terror was a plebeian method of doing away with the last vestiges of feudalism in a radical way," the idea suggested in several texts, but above all in "The Bourgeoisie and the Counter-Revolution," an 1848 Neue Rheinische Zeitung article (Löwy, pp. 116-117). In truth, the Terror during the French Revolution had all these elements and more, (and so did the Terror during the Iranian Revolution, which killed not only the true enemies of the revolution but also Iran's own "enragés," who had earlier called for terror themselves, perfectly recapitulating the dynamics of the French Revolution), so it was no wonder that Marx hesitated to settle on any one of them.
* "[T]he decrepitude and death of the body politic" describes the USA today perfectly.
<http://www.marxists.org/history/france/revolution/robespierre/1794/terror.htm> Republican virtue can be considered in relation to the people and in relation to the government; it is necessary in both. When only the government lacks virtue, there remains a resource in the people's virtue; but when the people itself is corrupted, liberty is already lost.
Fortunately virtue is natural to the people, notwithstanding aristocratic prejudices. A nation is truly corrupted when, having by degrees lost its character and its liberty, it passes from democracy to aristocracy or to monarchy; that is the decrepitude and death of the body politic. . . .
But when, by prodigious efforts of courage and reason, a people breaks the chains of despotism to make them into trophies of liberty; when by the force of its moral temperament it comes, as it were, out of the arms of the death, to recapture all the vigor of youth; when by tums it is sensitive and proud, intrepid and docile, and can be stopped neither by impregnable ramparts nor by the innumerable armies of the tyrants armed against it, but stops of itself upon confronting the law's image; then if it does not climb rapidly to the summit of its destinies, this can only be the fault of those who govern it. -- Yoshie