In the kitchen, you can certainly replace parsnips for carrots in many recipes for a milder, more subtle result. For roasting and mashing, however, parsnips are interchangeable with root vegetables from the Brassica family like turnips and rutabagas. But enough about substitution -- it's the parsnip's turn to shine.
What does produce have going for it? Everything. But it's saddled with the geeky rep of being good for you. We've shown time and time again we just don't care. Considering how eager vegetables are to make friends and get along well with others, though, it seems kind of cruel to keep dismissing them.