Its stability is very good. I have not heard any of my customers having issues with FlashArray. It is very solid. They claim 99.9999% availability. I haven't had any problems with outages with my customers.
They have another product called FlashBlade, which is a different type of storage appliance that Pure does for unstructured files. FlashBlade doesn't rank as high in reliability as their flagship FlashArray product does. The FlashBlade product is a notch below. It is a newer product or code, and I have heard of some issues with it.