UPDATE: I've been wearing these for a couple of weeks and three of the spikes/studs have sheered off. This is very disappointing. I wouldn't now give them five stars but I can't change that.
I think these are a bit expensive for what they are, but they work very well and make a huge difference on icy pavements so they're easily worth it for me. I live at the top of a long and very steep cobbled snicket/alleyway and felt like staying home rather than attempting to get down it last year after several falls.
I couldn't go on like that, so bought these. The first snowy/icy day and I'm converted. I went straight down the hill with no slipping at all, and strode confidently about the icy pavements while everyone else was doddering about like old folk.
They're very quick to slip on, stay put, and easy to take off thanks to a big tab at the back for that very purpose. The six carbide 'spikes' don't look much but really dig into the ice.
They come with a handy re-sealable plastic carry bag so you can put them in your pocket when they're wet. They don't take up much space in your pocket.
They are a bit odd to walk on ice-free pavements but that's to be expected. You can take them off in seconds if you need to without sitting down or removing your shoes.
Overall, they give you the confidence to walk safely on ice, and if you've ever fallen over on ice, you'll know how valuable that is.
One small snag is that they leave your hands smelling strongly of rubber for ages afterwards if you don't wear gloves when you pull them on and off.