I love the reins I bought for Ds1, that I then also used for Ds2. DS1 loved them too - he knew if he got them on, then he got to walk and explore, and that if he fell, I'd catch him before he hit the ground.
I used them regularly until he would hold my hand properly without trying to wriggle free - I guess he was around 2.5- 3 when that happened - but I kept them in my bag for much longer in case he played up. I used them for when we went to the UK (I took him on my own) in the airport, to stop him disappearing off - and I used them when we were near a river in the UK and he was being silly on the bank. I think he was just over 4 the last time they were used on him!
Then Ds2 - he actually liked to have them on, he would ask to have them, again because he knew it meant he could walk and I'd catch him without falling. He hasn't worn them for some time now while out walking (he's nearly 3) but I still have them in my bag.
They also have another use, because of the detachable strap - when you're at a restaurant, they can be used if there is no harness on the chair/highchair that you have to use - I just put the reins harness on him, detach one end, wrap it round the chair back a couple of times so that he can't climb out but isn't fully tightly restrained, then clip it back in.
I bought mine from Boots, 7+ years ago - like these ones except mine are orange and bright turquoise - and they've stood the test of time really well.
I have no patience with the concept that they're somehow a bad thing - I'd far rather keep my child safe (and remember MrsPresley's tragic story very very well -
for you) and sod what anyone else thinks.
I'm also less of a fan of the backpack variety, ditto the wrist straps - part of the value of reins for me was preventing my sons having nasty falls while learning to walk - they'd still trip, but not fall because I had the reins looped round my hand. Also saved my back, because I didn't have to bend to hold their hands to stop them falling.