These little Anemometers are great. They are much cheaper than the Kestrel equivalets and offer all of the features below:
If your going to get one make sure you get the Summit or if you're feeling flush the Pro. The other models don't offer pressure and Altitude readings which are useful for shooters.
An anemometer is a very useful item and all long range shooters should have one. I used mine whilst shooting the Steel Challenge at WMS a while ago and it was invaluable. There were some very tricky winds but at least this gave me somewhere to start as well as providing me the alt, temp and pressure information to plug into my iPhone ballistic software.
The only thing I don't like about them is they turn on every time you push a button so if you've got it stashed in a pocket or rucksack etc it'll be turning on every two minutes and the battery won't last as long. Although it is claimed to last 4 years, if I leave the battery in it lasts about 6 months which is still useable but also very annoying when you want to use it and the battery is dead. It would be much better if it had a cover of a dedicated on/off switch.
All of that said, if money was not object I'd have a Kestrel 4500 NV with Horus ATrag Ballistics. It has built in ballistic software as well as all the usual features but at £450-£500 I think I'll stick to my Brunton and iPhone for now.