The other day I was reading about cherimoyas at Food Blogga. It's an ancient Incan food, and apparently Mark Twain described it as "the most delicious fruit known to man". When I saw one at Meijer yesterday, I had to try one out. The one I bought was already ripe (it was slightly soft and brownish). To eat it, you cut it open and scoop out the flesh, avoiding the big seeds.
They have a distinctive tropical taste. I tasted banana, pineapple, and coconut, and maybe some mango. It's not overwhelmingly flavorful, and only subtly sweet. It was just enough to make me picture Hawaii. I wouldn't describe it as the most delicious fruit (especially at $4.99/lb), but that might be because it was shipped across the country to get to me. I'm glad I tried it out, though, and I'm always up for a fruit adventure!