Soursop has a somewhat soft green or green-yellow skin, covered with soft spine bumps (the spines are also really soft, and usually break off). It varies in size somewhat but is about the size of a coconut. The hard black seeds are a flat oval shape, and inedible. The flesh is offwhite, and quite soft. It’s juicy and a little grainy, with some stringy fibers like you might find in a very stringy mango. We tried eating it with a spoon at first because it is so soft, but the fibers made that not work out very well. It smells like banana, pineapple, and gardenia flowers. It tastes, again, like banana-pineapple-gardenia, plus has some sour and acidic flavor. We’ve had soursop juice before (it’s pretty easy to get, soursop also grows in Mexico and multiple places in South America) and the fruit basically tastes exactly like the juice, just with more fiber.
There’s more information on soursop here: https://en.wikipedia.org/wiki/Soursop