When a call arrives and the screen is off, the ICS lockscreen is displayed first, you have to unlock it sliding the locker the normal way, then the incoming call screen is displayed and only now you can answer or decline. The ICS lockscreen introduces an additional step to unlock the lockscreen before being able to answer or decline the call
More generally, with the vanilla, the ICS screens are in the middle of the Sence screens : for example, the phone call dialer is ICS, but the screen to enter the SIM code is Sense ... The notification drawer is Sence, the Settings are essentially Sense but some parts are ICS (the Android Keyboard for example) ... a little bit confusing IMHO.
All you have to do to get the ICS lockscreen is to unselect the HTC lockscreen item.
The Google lockscreen will automatically be added (The Google lockscreen item can't be selected).
Edited by raph santerre, 24 May 2012 - 05:40 AM.