Google describes it as a positive feature where in application will be able to access WiFi radio even when it is turned off so that they could locate the location of the device.
However, many now expressed their concern that malicious applications might exploit this new functionality.
Moreover, WiFi is considered as one of the major power consuming features in smartphones and tablets. So if it will be kept turned on, obviously the battery in smartphones and tablets will drain our faster than usual.
Now will Google resolve this or add something to counter the issue is to be seen, but for the time being users must carefully read the application access and if they feel something suspicious they should avoid installing that application.