Insofar as longevity is correlated with reducing suffering due to chronic pain and old-age disease, I think it's great.

But there is one problem with longevity: Boredom is a thing. When you are a toddler even a small piece of paper or a string can excite you. But then you get bored and you need to find something else. I am almost 40 years old now and pretty much all my drive in life is my two kids. If I didn't have them I doubt I would find reason to get up from bed every morning. If I had to live forever or for a very great number of years I believe life would become a burden. It's always been possible to be old and sick and thus unable to do things you crave. But I fear one day it will be possible to be young (in body) and healthy and unwilling to do things because you've done them all before too many times.