They're beautiful but deadly to roses and quite a few other plants.. A newly opened blossom is like a delicious bite of candy, it seems. So, what do you do? A fence is one solution. Spraying with a mix of one egg, a quart of water and some smelly essential oil, like thyme or rosemary, works quite well.
Of course, you can landscape with deer-resistant plants and there are quite a few that seem mostly immune to their browsing. Not absolutely, forever one hundred percent. Seems like they'll try anything occasionally, especially if they're hungry, but you're pretty safe with herbs like rosemary and quite a few other plants.
And, for some reason, rugosa roses seem immune. Or perhaps they simply grow fast enough to recover from the predation.