There's no definitive answer to be honest (as opinion on this thread suggests).
For our own salon, leaflet drops worked better than expensive newspaper and radio ads and we could measure the effectiveness as we'd suggest people bring the leaflet back for a specific discount- this is a very important aspect of any marketing, if you can't measure its effectiveness, its total guesswork and conjecture.
There are so many variants in the demographics (in terms of location, ages, disposable income etc etc.) of where everyones businesses are, its almost impossible to say if it'll work or not.
The only way you'll know for certain is by trying it.
But don't expect miracles on the first drop. Its a culmantive effect as people come to recognise your brand- you should find (if you space the drops appropriately, not too often, not too long between) that it gradually becomes more effectivec over time (which is a general principle with all marketing methods).
But, make sure you give every chance of making the leaflet work. I've seen so many examples of a poorly executed leaflet failing- and then people blaming the technique itself!
Have a read of this if you need help
Designing an Effective Leaflet
Paying particular attention to the first tip
