It is kind of like Ayn Rand and John Locke in practice.
The importance of Schopenhauer is great. Also German Idealism [i.e. Kant, Fichte, Schelling, et al.]. I still have a great deal of trouble with Hegel. I see most Marxist principles and Leftist Socialism stemming from him. I can not figure out if the trouble was people misusing him or if there really was something "off". This is not an irrelevant question. The fate of about 100 million people perishing under socialist governments in the 20th century seems to raise some some doubt about Socialism.
From a Jewish point of view German Idealism is important because the basic structure of Metaphysics of Torah is mainly Neo-Platonic and Aristotelian. [That is the metaphysical backbone that is clearly stated by Saadia Gaon and the Obligations of the Heart and Maimonides and the Ari.] There are questions about this structure which need to be addressed and not just papered over. [The general way to deal with the Rambam and Saadia Gaon is to ignore them an pretend they did not write anything about the basic metaphysical structure of Torah.]
That is,- there is a reason why Saadia Gaon and the Rambam adopted the Neo Platonic point of view. The same reason gives us today a further reason to find support for the Torah point of view after that much of the medieval concepts used by the Rambam and Saadia Gaon seem quiet,.. well..--medieval. That is,- axioms that do not seem all that true anymore.
[After I wrote the above essay I thought to mention some points. Mystic experience is not what the holy Torah is about. Because the Rambam rational approach is not interesting to people they go instead to mystics. The trouble is most of them all are teaching the teachings of the Shatz in different form.]