I have heard that it is mainly a cleanup of the Honeycomb release so that the phone and tablet OS are merged back into a single line. There were some improvements too, like resizable widgets... wait Go Launcher already does that
yeah, there's not enough known right now, i don't think, to have an opinion. The idea is to combine Honeycomb, Froyo, and Google TV (i think?) into one OS and be unified. Of course improving upon it all too I would imagine.
google is going to continually develop this os. every release since 1.5 has been a marginal improvement in performance/battery life/utility etc... ice cream sandwich will be no different. plus they announced a ton of sweet new features.