Hegel comments negatively on this argument in Lectures on the Philosophy of Religion (vol 1. p. 227)
It is frequently said that in his will man is infinite; while in his understanding, his power of know ledge, he is finite. To say this is childish; the opposite is much nearer the truth.
On the same page, Hegel explains his objection to this position:
In willing, a man. confronts an Other, he isolates himself as an individual, he has in himself a purpose, an intent with regard to an Other, he behaves as if separated from that Other, and thus finitude comes in. In his acts man _has an end before him, and such action essentially requires that the content, the end, should exist, should lose the form of an idea, or in other words, that the end in view being, to begin with, subjective, should have this subjectivity taken away from it, and thus at length attain to objective existence.
I will try to reword that here. Hegel maintains that an act of will requires the self to make itself particular (thus denying premise 4). It's a bit hard to follow but the basic idea is that to will something requires having a particular objective and that to have a particular object means that the self must also take up a particular position. In the process, the thing we will loses the formal nature that makes it universal.
An analogy might help, in a sense, someone can will "to get a girlfriend" and that seems pretty broad, but the moment he wills towards getting any particular girlfriend, he's not willing an idea that's universal but a particular thing.
Moreover (as Philip Klöcking helpfully notes), Hegel believes this permeates the activity of the will. When the will engages in acts of willing, it always does so by selecting an object and thus restricting itself. Thus, for Hegel, will is by definition finite.
For Hegel, this is particular bad because the human self is Spirit (a technical term for Hegel) which is unlimited and infinite. And it can achieve this unlimited and infinite nature only in knowing the infinite (this is a central claim of his Lectures on the Philosophy of Religion but is made explicit several times between pages 200 and 300).
Hegel's denial of premise 4 is an en passant move in his larger denial of premise 3! Interestingly, Hegel thinks that we can know the infinite specifically as God, and that the mistake is to know God as a particular. In the process, the self qua thinking Spirit is at one with the object of Spirit (rather than being up and against an object as in the case particular acts of will).
Interestingly, this to will is to make the self finite and particular is also central in Hegel's critique of Kant which can be found in Phenomenology of Spirit, Natural Law, Philosophy of Right (which may also make oblique reference to Descartes model but no where that I can recall is as clear as the above passage on the Descartes' angle). (For further reading on its success or failure, there's Allen Wood, Hegel's Ethical Thought and Kant's Ethical Thought (along with an article in Ethics); Sally Sedgwick has a few article that seem to repeat similar themes; it's also touched on in commentaries on Hegel's works such as Charles Taylor, Hegel (1975), Dudley Knowles' Hegel and the Philosophy of Right , Adriaan Peperzak Modern Freedom, and articles by Kenneth Westphal and Thom Brooks)
