This is research. You should be focusing on "what's new, and is it interesting" not "is the thing they made a good product".
That said, Li-S typically looks good with respect to potential cost if mass produced (cheap materials), and density metrics. The papers abstract has absurdly good things to say about charge rates. All-solid batteries are typically going to be very safe. So at a glance this research is at least in a very commercializable direction.
>All-solid batteries are typically going to be very safe
Sulfur melts at 115 °C though, so when it overheats, it's not solid anymore. But then, it's apparently not just sulfur, but sulfur embedded in some other stuff, so who knows.
That said, Li-S typically looks good with respect to potential cost if mass produced (cheap materials), and density metrics. The papers abstract has absurdly good things to say about charge rates. All-solid batteries are typically going to be very safe. So at a glance this research is at least in a very commercializable direction.