At a family function the other day, a distant relative gave my mom a couple of cherimoya fruit to take home and try. We cut one up and had it for dessert tonight. I have to say, it's kind of awesome.
Delicate, hard to cultivate, and indigenous to the Andes region of South America, cherimoya are rare and expensive. The site californiacherimoya.com sells them for $10 a fruit (down from $15).
It's hard to describe the taste. I understand why some might say it's a combination of pineapple and banana, with a soft, almost runny cheese-like flesh. I taste something more akin to a pear, or even an asian pear, that is intensely sweet and a sharpness in the background. I bet it would make an awesome sorbet.
Definitely try one if you get the opportunity!