While I had to learn that Microwave ovens don’t magically work on the resonant frequency of water molecules, they do work by inciting motion in dipole molecules, and water with those little H atoms hanigng off to one side is dipolar, so microwaves are rather good at heating them up. This means that you’re sort of working in the same realm of temperatures and humidity as steaming or even boiling, for good or (mostly) for ill.

Heating frozen food specifically engineered to come out okay from a microwave? Well, it’ll come out okay. Re-heating soup or re-steaming tamales (mmmmm. tamales…)? Pretty decent. Heating up anything that wasn’t meant to have “wetness” as a major part of its mouthfeel will go poorly, often disastrously if you don’t try to work around the microwave’s limitations.