The only thing that the Palace loses to the Demon King's Castle is its size and the details of the statues standing on each side of the hall. Other than those, I believe even Ilschevar will admit the Palace is better.
The eight statues standing on the sides are nowhere near as tall as those of the statues of the Heroes who managed to kill the former Demon Kings of Verniculos Kingdom at the Path of Reminder. They are also not as well-sculptured, however they still look impressive.
I don't know anything about who are these guys that are worthy enough to have their statues displayed here. I am inclined to believe however, they are the predecessors of Lysimork, who have rested in peace.
They are not as many as my predecessors, but it is not unusual considering how recent—compared to how long Demon Kingdoms have ruled a half of this world—Lysimork is founded.