Depends where you live if winters are worth it or not. The last 2 years in London I didn't see a single drop of snow, though the year before that it was chaos - 2012 I think was bad. Suddenly winter tyre sales went through the roof - but really? Paying £500+, spending all that time in the cold swapping the tyres and then only using them for a week seems a waste of money.
If I lived somewhere - i.e. Scotland - where it was almost guaranteed to snow every winter then I would definitely buy them.
What about getting tyre chains and keeping them in the boot? Saves the hassle of swapping tyres every time.