Having bought and used both these spikes from Springyard and the popular Get-a-Grips, I prefer these for three main reasons.
Firstly, they're cheaper; secondly they have one more spike (5 at the front instead of 4) which I feel gives a better grip and finally, in my opinion, they're easier to put on the shoes (a bit more stretchy). However, they don't come with spare spikes but then the spike construction is slightly different and they seem less likely to be damaged/snapped off.
I've only tested these once (versus several times with the Get-a-Grips) but I'm very impressed. Clearly the effect of the Swedish winter has positively influenced their design. They come with a nifty little draw-string black bag (which will probably degrade eventually), but is fine for the job.
Whilst they recommend putting them on shoes/boots before you put them on your feet, it's not essential to do it this way. It's also not difficult removing them without having to take ones footwear off. Definitely a plus when they're all mucky with snow and mud!
It's a big comfort keeping some in the car for when you get caught out by the weather. I strongly recommend them.