I have used pressure cookers for a long time and this is my favorite one. The size is great. For those, like me, who didn't know how big to go, the 6 qt cooker is good for curries when you are using 1-2 pounds of meat but it can also do larger quantities. I needed a larger pot and I have a 4 qt, which is too small for my needs.
It is a heavy stainless steel and I would steer away from aluminum due to the nature of its use. Aluminum won't last as long, and there is a reason it's cheaper than the stainless.
I really love this, I would recommend it to anyone...