I agree with comments above. They were quite sweet, with a somewhat berry-like flavor. Texture-wise they were gelatinous as has been mentioned above, but quite juicy, some nearly watery. Apparently it is a breakfast food in the rural area of Jamaica where we were. I preferred the white to the purple; the purple had 4-6 seeds as compared to an average of 2 seeds per fruit in the white variety. There were so many seeds in the purple ones that you could not cut straight through the fruit, you had to cut most of the way through and sort of tear it in half. Also, the pulp was adherent to the seeds in the purple ones, while the seeds popped freely out of the white ones.
All that said, the one abiu I had a Ian's was better than any of the star apples I had a couple of weeks ago. It would definitely not beat a good mango or lychee in my book.