Here are some tips about microwave cooking:
-The microwaves generally only penetrate 2 inches into the food, so make sure food pieces are not too thick. Uniformly sized pieces are best.
-Foods cook faster at the edge of the dish than in the middle, so put denser foods on the outside for even cooking. Place tender portions of vegetables, such as the flower portion of broccoli, towards the center.
-Consider standing time when cooking vegetables. Food will continue to cook for a short period after you remove it from the microwave.
-Generally, microwave cooking produces a high-quality vegatable, but there are some that come out better using conventional methods.
-Microwaves do retain water soluble vitamins and minerals a lot better than boiling, although I know that spinach is an exception in regards to its vitamin C content (if a small amount of water is used in boiling).