While wikipedia references shown some ethical practice followed by the major three businessmen including JP Morgan, the second reference an obituary speaks of both good and bad things. As per that he was instrumental in bringing the economy of USA by obtaining railroads and improving their standards. More can be seen from the sites:
In American history the "Gilded Age" refers to the post-Civil War and post-Reconstruction era, from 1865 to 1901, which saw unprecedented economic, territorial, industrial, and population expansion.
The entrepreneurs of the Second Industrial Revolution created rich industrial cities in the Northeast brimming with new factories, and to the rise of super-rich industrialists and financiers such as John D. Rockefeller, Andrew Carnegie and J.P. Morgan. Their critics called them "robber barons", referring to their use of illegal and unethical tactics including bribery of politicians and newspaper editors, and the ruthless employment of unregulated virtual monopoly power against competitors.
2. During America's Gilded Age, mere mention of the name J.P. Morgan conjured associations with success, opulence, corpulence and excess, attached to a man who rubbed elbows with European royalty and was able to spend more money to buy Carnegie Steel than the federal government could budget in a year. Powerful enough to reorganize Wall Street at will from his favorite table at Delmonico's, Morgan was painted a robber baron by the press and a suspicious and envious government, though Morgan actually parlayed his assets, industries and influence into advancement of the nation as much as to further his own interests. Morgan became the financial backer of an often skeptically viewed inventor, Thomas Edison, and devoted nearly two decades to funding the inventor's work with electricity as well as the foundation of the Edison General Electric Company. It was a blow to Morgan, who had supported Roosevelt's New York gubernatorial campaign both personally and financially, only to find himself object of a federal lawsuit pressed against his Northern Securities Company. Morgan's profits and flamboyant lifestyle were the focus of attention, media tirades and outright resentment which overshadowed his work as a pioneering philanthropist. After a long and exhausting 1912 Congressional Committee investigation that was predominantly unsuccessful in damaging the Morgan reputation or revealing illegal doings by the billionaire, Morgan was left with his health in tatters.