When I got my Yaktrax walker I wasn't totally convinced, I received them as part of a promotion, now we have had snow which has turned to ice I'm impressed.
The Yaktrax slip on the the bottom of your shoes easily, you do have to take care as to which way round they go on as this is important apparently.
I first tried them on a quick trip to the local shop in relatively fresh snow, although not really necessary they did provide confidence whilst walking down the street. My second trip however they did really help, the pavements were compacted snow which was incredibly slippery without the Yaktrax. Once I had attached the Yaktrax to my shoes the situation was completely different, no slipping at all, had I wanted I'm sure I could have run.
All in all I am very impressed and defiantly worth the retail price of £15.