Microwave isn't that good at reheating food if you're the type to just dump the cold leftovers in 1 pile on the plate and expect the microwave to reheat it evenly.
Some parts will be overdone, some parts may still be cold/warm - especially the center of the pile. I would advise you break up/loosen the pile of food.
You may have to zap it at a lower power for a longer time, then mix the food, then zap it again - which is what I do to get it hot throughout.
I also add a bit of water to the food to be reheated, as the microwave can dry out the food. If you use a cover over the food, this added water becomes steam which will help the food heat up and keep moist - so not good for heating up fried/crispy foods.
Some types of food - especially squid/prawns can explode while microwaving. I bury them at the bottom of all the other food to prevent that.
You can't microwave using metal containers, only microwave safe plastics and ceramics, glass, etc. Metallic decorations on the caontainers are also not advised.
Oily foods being microwaved may also stain/discolour the plastic containers.
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A steam oven can make the food much wetter than you desire - the steam will obviously add moisture to whatever is being heated up, so it won't dry out like a microwave can.
It does take a longer time for the water to heat up to become steam, so depending on the quantity of food to be reheated, it may take quite a while longer to completely heat up, compared to a microwave.
Generally steam reheating doesn't need the food to be loosen up or mixed unless the food is really dense and all clumped into 1 pile.
I wouldn't advise using a plastic container to heat up food with steam - I transfer the food to a metal container for steaming.