For me, these are the advantages of ICS over previous android versions:
* The biggest advantage of ICS is the fact the the UI is fully HW accelerated. You can now see how smooth it is and what the adreno 200 gpu via opengl can do for these devices.
* Browser rendering is now tiled and faster/smoother. Also tabbed browsing is a plus.
* Network data statistics and ability to set limits so that you don't get charged my mistake.
* The UI is really beautiful and the navigation has got better. Also all the core apps are redesigned and improved
ICS does require more RAM though