Started using them when I was 24 or so, and working in Outdoor Education (13 years ago!) - I've done some damage to my knees over the years from mountain biking and walking, so anything to help is a good thing. Combined with decent boots, Superfeet and Poles, I'm all good.
I use a pair when I'm walking with an overnight or longer pack, and sometimes on day walks (wife has banned me as I go even faster with them than normal). I got some cheapo
Decathlon ones in the UK, that did the job. (By the way, watch out Anaconda when Decathlon get up to speed completely...)
Like others, I used to work in Outdoor Retail, so I know the hype about the different brands (Leki, Black Diamond to name a few), but I also know how to fit them, and that makes a world of difference! You need your arms to be carrying a tray of beers back to the table... Don't forget to sink the spike of the pole into the ground a bit as when you walk that's what will happen, so set it correctly. Also use the loops on the handles - put your hand up through them so the strap sits in your palm, and allows your wrist to pull the pole down a bit.
I found that walking with an alternate swing worked best for me, and