When I bought my Motorola Moto G2 in January 2015 it was powered by Android 4.4.4 and I was "then" very happy with this phone.
Yesterday (on 19.02.2015) was I the Moto G2 then upgrade to Android 5.0.2. However, I have received no update notice, but had availability on "Settings" -> "About phone" -> Check "System Updates".
After the update was available or was found, including the highlights of the update were displayed. Furthermore, a message appears asking if the new system software to be downloaded or not.
The update to Android 5.0.2 includes about 385 MB and was downloaded with me via a WLAN connection.
After a successful download again a query whether you want to install later or now follows.
After installing Android 5.0.2 All settings were in my case and data such as SMS messages, wireless keys, phone contacts, ringtone selection .... yet. A backup I had previously made but for security anyway.
Only the Bluetooth pairing which I need for the speakerphone in my car, was not found, but could easily be re-established.
The new system software works pretty fast and makes me no problems.
Notification of SMS received or missed calls I personally find much better than Android 4.4.4.
All in all, I am also after the Lollipop update very happy with this phone and the device would buy again.
Greeting Markus