That's meaningless in the grand scheme of things, unless you think sex is supposed to be completed in a matter of minutes. In fact, this slowed response means that men need foreplay, just as women do. This can be a blessing to your partner and to you. As men reach their late fifties and early sixties, it's possible that the erection may not be as hard or as large. But once fully excited, the erection will most likely be hard and steady.
Many men find that manual stimulation by their partner is needed to gain a full erection.
As men age, there's likely to be a reduction in the amount of seminal fluid, but this, too, is meaningless. And, in fact, it may be a bonus. Less seminal fluid usually means that men can delay ejaculation for a longer period of time. Again, this benefits both partners. It's common for the length of love making to increase as men age.