Matices means nothing is neither white nor black for sure.
A: ¿Viene Pedro a la fiesta?
B: Me dio un "sí" con matices.
B: Que vendrá si termina a tiempo con otras cosas. Lo intentará, pero no se compromete porque otras cosas pueden interferir.
or you could say a smartphone is the best one
con matices, meaning that is the best one if you are going to use for this and that, but not that much for that other task, because it doesn't perform that well on that.
matices could be the rules by which you are judging something or someone. Is like saying
you have this **but** with or without that other thing in consideration.
In Spanish that words conveys the meaning of
shade... An aspect or variation in interpretation that could change the meaning of something, or a shade that makes things neither white nor black.