Contemporaries and historians have had differing opinions regarding Eggenberg's character: seeing him as a man ... who is successful at everything he does, a fellow of good fortune, with a reputation of being completely loyal to the Emperor, highly gifted and reliable, but also a corrupt and slippery customer.

A famous associate of Hans Ulrich's, Johannes Kepler, also received a first-rate education at the Tübinger Stift and went on to write his first work, Mysterium Cosmographicum, while teaching in Graz.

[3] In his positions as the President of the Geheimrat (Privy Council) and Lord Chamberlain (Obersthofmeister) to his new Emperor, Hans Ulrich, the son of a merchant family from Graz, had risen to become one of the most significant and influential statesmen of his time during the period of the Thirty Years' War.

[3] His office also prompted him to commission the conversion of the medieval family castle on the western edge of Graz into a new and glorious residence, Schloss Eggenberg, to appropriately represent his new status.

As an imperial minister, Hans Ulrich had skilfully succeeded in guiding his master on the throne despite facing numerous dangers and constant upheavals during these times of great change.

He slowly and consistently worked on his ideas of a united "empire", which he saw as a strengthened central imperial power, at the expense of the feudal interests of the old noble families and the desire for autonomy of the princes of the realm.

On 1 August 2010, UNESCO expanded the registry listing of the City of Graz - Historic Centre to include Schloss Eggenberg among the World Cultural Heritage Sites.