I sliced one of my Glenn mangos a little too early last year, but still found the flavor to be outstanding. It was crunchy, sweet, and a little bit sour. I've spoken with many people around here that prefer to eat a mango before it becomes ripe.
However, I have a sweet tooth.. so, I prefer my mangos fully ripened.
A fully ripened Nam Doc Mai mango has a hint of spice to it. I LOVE it!