It's nice to brainstorm with too, but you have to know what you're doing.
It gets stuck on certain things for sure. But all in all it's a great productivity tool. I treat it like an advanced auto complete. That's basically how people need to treat it. You have to spend a lot of time setting up context and detailing what you want.
So does it save time? Yea, it can. It may not in every task, but it can. It's simply another way of coding. It's a great assistant, but it's not replacing a person.