Of course crying is good for you. Bad shit happens to people all the time, you better release so you can recover! But to me crying is exhausting and it feels like my heart is gonna stop. Not relaxing at all. Always feels like shit. But it's natural and you do feel better when you've gotten over the fact that made you cry in the first place.
While crying is good for you, but crying “all the time” is not. If you are literally crying all the time, please seek help. It could be a sign that you have an issue bigger than your ordinary saddening situations.