Comment it's all good (Score 3, Informative) 194
Unique device ID doesn't violate privacy whatsoever since there is no link to your name, address, etc..
It DOES however provide a great way of ensuring "trial" or "lite" apps handled by a server and doing what you intended in say limiting results or whatever.. it also is good for internal logs since you can refine your app by looking at how the app is used, both overall as well as individual patterns.
You don't need GPS, personal or any other information at all to provide LOTS of benefits and an IMPROVED app once you have a access to a unique ID that doesn't involve registering username or whatever as annoying websites do.
I think a credible business would disclose in an open way what server transactions are involved on a per-app basis and with our new server suite being rolled out I know we will provide a web page per app detailing this so it's all open and above board and the benefits given.