It's good if you have your phone in an office environment and aren't planning to drop it, and simply protect the screen from dust and basic things.
Personally i would never use it, as there's not nearly enough protection for my needs
I had one on my s4 and absolutely hated it. It stopped sitting flush with the screen when placed on a table so I bought a SGP slim armor view case (I think that's what it's called). Because there is a kind of clip on the front, it doesn't flip open on its own and I don't need to worry too much about throwing the phone into my bag.