Ive been using ICS on my Nexus S for about 48 hours now. I've been an Android user for about 2 years, and was a webos user before that.
Anyway, I wouldn't say with ICS one has to unlearn how to do things. It is still android, and still feels like android, it just feels like the next step in it's evolution. In fact, I feel that Google has taken some of the good things of the OEM customizations (sense, blur, touchwiz) and implemented them natively. So now we have ICS, I'm liking it quite a bit so far.