We love our microwave, and it's in frequent use in preparing dishes. We have a small commercial machine, so no stupid turntable, which makes life much simpler (and cleaning easier).
We normally use it to par-cook vegetables prior to assembling the completed dish. But it also cooks carrots, courgettes, mushrooms, aubergines, leeks, onions (when you want them soft but not browned), and many other veg better than any other device. It certainly keeps the nutrients and vitamins better than any other method.
It's also good for steamed fish, although many recipes need the skin to be crisped briefly under the grill. I guess a combination oven would do that too.