when you can get fresh, ripe pieces of perfect mango, it's fantastic. trader joes sells it already sliced and packaged, in case you're interested. make sure there's some kind of liquid in the container otherwise it'll be as dry as can be and not tasty at all.
if you feel adventurous, you can always buy a regular mango and cut it up yourself, but negotiating around that huge seed in the middle takes some skill/experience. but man, if you get the right one at the right time, what a payoff.