Although gorillas' hearing capabilities are probably not any better than ours, they do need to be extra sensitive to sounds because they live in dense forests which conceal visibility of potential predators. So hearing is important to gorillas for locating one another and for detecting danger. For this reason, gorillas often respond to strange noises that they aren't used to.
Gorillas see mostly as well as we do. Their eyesight is used for finding and identifying food, as well as looking out for danger. Because gorillas are herbivores that search for food in the daytime, they probably have color vision which is useful for detecting the difference between ripened and unripened fruits. Like humans, gorillas also have both eyes facing forward, instead of one on each side of the head. This binocular vision allows them to accurately assess distances and depth. Gorillas and humans both have a specialized area of the eye called a fovea, which contains condensed light-sensitive cells that aid in good visual acuity.
Gorillas probably have a better sense of smell than humans do. They are able to detect strong odors in the environment, like human sweat and the scent of an unfamiliar gorilla. Males use females' odors to determine their reproductive statuses. Also, Silverbacks emit a scent from their armpits when they sense strangers around them.
Gorillas probably have a less sensitive sense of touch than humans do, and they are less tactile than other primates. The hands and feet of gorillas are protected by hair and very thick skin so that they can pick up nettles (a plant covered with stinging hairs) and be stung by wasps without being hurt. One of the main reasons gorillas use their sense of touch is for grooming. Mutual grooming often takes place between mothers and offspring, and sometimes females groom Silverback. This grooming keeps the thick hair free from dirt and parasites, and also reinforces social bonds.
Gorillas most likely have the same tasting abilities as humans do. Their tasting capabilities are important so that they can learn the differences between poisonous and non-poisonous plants.