I have a Nexus S (european edition, no super amoled screen), I upgraded to ICS in December but I think it has problem because it restarts itself very often and I don't know what have caused this behavior.
Anyone have similar problem?
Yes many people experienced problems. Have a look at: http://www.google.com/support/forum/p/Google+Mobile/thread?tid=1c21a7e3690388b0&hl=en
where a Google employee is asking for information on the problems people are having and asking them to submit bug reports. Here's the generic bug report link for Nexus S with ICS: