You may have already covered the basics like whether or not it worked, how much it worked if it did, if you loved it or wanted to throw it across the room, the aesthetics of the ring off and on your package from both of your perspectives, and the overall workmanship of the cock ring. So I'll wander into the more specific questions I'd ask you.
Just off the bat, as a woman, I'd want to know how it felt to your partner. Some soft rings with hard bullets can be painful when we're on top, while others feel good that way, depending on their size and shape. Does the hard material feel good? Is it irritating or painful or annoying? Or is it just not noticeable except for in its effects? Gentle temperature play is possible with a metal ring; if you dare to go there, how did it go? Did you notice, and did your partner?
From your perspective, was it heavy enough that erections felt like a "cock-ups" exercise? Was the weight distracting? Could you comfortably wear it for the recommended time, or did you have to take it off sooner?
If you absolutely had to find a flaw (or a few), what would they be?
If you had to find a way to improve the ring, what would it be?
I hope these help. Can't wait to read your review!