This thread shows that fruit tastes are extremely varied, and that one person's overrated fruit is another's favorite.
Spanish lime/Mamoncillo/Genip (Melicoccus bijugatus) is one fruit I believe is overrated. I like the taste, but the flesh to seed ratio is appalling.
I find jackfruit overrated. Ones that I have had were likely picked too early and had a slight savory/onion aftertaste with only a mild Juicy Fruit gum taste. Plus, cutting one of them up makes quite the mess.
Other people swear by Gold Nugget mandarins and Minneola tangelos, but while I do like a good Sumo (Dekopon), my citrus tastes run towards grapefruits and pomelos. If I could buy those for the same price as tasteless navel oranges, then my grocery store would not be able to keep enough of them in stock for me.
I have never had jaboticabas, but I walk right past the regular seedless grape section to buy Concords, Thomcords, and muscadines, all grape varieties/species with unique, strong flavors that some people love and others cannot stand. I can see jaboticaba varieties being similarly polarizing.
Other fruits mentioned in this thread, such as mamey sapote and soursop, are ones I like a great deal.
I agree with the original poster, Gone tropo, as well as others who have replied in this thread, that lychee and rambutan are some of the best fruits in the world (both are in my top 10 favorite fruits) and most fruits, even very good ones, suffer in comparison to those.
Taste in fruit is subjective, but it is fun to see what some people like and others dislike.