It's a Dutch brand, now owned by a Japanese brewery and made under license in Canada by Sleeman Brewery of Guelph Ontario, which was sold by the family to a different Japanese brewery but is now owned by a craft brewer in British Columbia. So who knows how close it is to the original.
Regardless, it is good beer, and easy to find in Ontario. In fact, it is one of the most popular beers in the Netherlands. People think of "Heineken" as the Dutch beer, but locals there think of it as their cheap export, and Grolsch is more of their national beer...
BTW, the "G is pronounced as a hard "H" by the Dutch, like you are coughing up a spitball... (I know, my wife is Dutch and she keeps reminding me on how to pronounce that name...) When in the Netherlands, that is the only beer I drink...