It was one of the first pistols to utilize a double-stack magazine, meaning that the cartridges did not ride directly on top of each other, but instead were housed staggered, so that more could be fit within the length of a pistol grip. This necessitated an increase in the width of the pistol grip, but this is a small detail for all but those with the tiniest of hands.
Still manufactured by FN to this day (and imported into the US by Browning), the Hi-Power is one of the most influential pistols in the history of small arms, having inspired a number of duplicates, copies, and other firearms that borrow features from it (chiefly the linkless cam system). It is renowned for its accuracy and reliability, and also its penchant for "biting" its user in the nape of their hand, between the thumb and first fingers, with its hammer.
The sophistication of Browning's design for the HP 35 is illustrated by his inclusion of a magazine disconnect safety (a device to prevent a negligent discharge when the magazine has been removed but a round remains in the chamber). Almost seventy years later, most of the modern "super-nines" do not have this feature.