I find my short-term memory is in decline, magnitude depending on specific circumstances. This annoys me, and to a lesser degree, my wife as well. Really, where did I put that damned can opener?
But I also find my ability to find connections among phenomena in my technical field has markedly increased. In addition to my subjective perception, there's an outside measure, the annual rate of patent applications my employer files on my disclosures, and consequent cash bonuses. About a factor of 4x compared to when I was 60. As well (per my wife's telling), I'm better at remembering anniversaries and other significant dates in our lives and those of our family & friends. Anecdata, of course.
I'd say my age-related 'decline' has been uneven regarding details of cognition/memory, and at the moment provides me and my loved ones a better quality of life - certainly not what I expected decades earlier. It's complicated, and I'll be interested to see what more the posted research leads to.