Had first at 38 and 2nd at 43 or 44, right now I can't remember. Oops. It's 01:30 here!
On the plus side: our older son is beyond delighted with the baby. He absolutely adores him and he's amazing with him. I think he thinks the baby is his rather than ours :)
Because the older one was at school already it was easier to manage, we only have one to wrangle in the mornings.
There's no jealousy. We do have to keep the baby out of the older one's Lego but they're far enough apart that I don't think they will fight over the same things.
I grew up as an only child and it's lovely, really lovely, to see the two playing together - the older playing with the baby and the baby always crawling after him. I hope they are friends when they grow up.
Negatives: There is an energy drop (but then, my energy levels are poor anyway so maybe others would notice it less).
The risks of something going wrong chromosomally are higher, but I'm sure you know that. It's probably a good idea to plan how you would handle it if you got news of a problem.
I got asked if I was the baby's grandmother more than once and more than twice, too
The delivery was completely normal, well normal except for no pain relief due to rapid dilation . The dilation then stopped just short of the pushing stage, but that's another story and totally unrelated to my age.
Overall: so so so glad we had the second, though due to HG there won't be a third.