Olive oil, poured after the dish have been cooked, is good. (Moderation is always the key.)
Using olive oil as a replacement for butter or your regular oil and heating it, you're going to feel more than a burn in your throat.
Personally, I love the texture it adds to my tomato sauce but the taste haunts my nightmares.
So, healthy and unhealthy both, simply because what does you good may do harm to your neighbor
And it also depends on how you use it!