Don't root your Nexus S just for the version of ICS thats available now. Too many apps don't work for it and can't be utilized. I attached a few pics of my Nexus S rooted running ICS and I'm about to roll back to GB 2.3.6 and be done with it until the official drops.
I can tell you this about the ICS rooted versions, they typing and keyboards and spell check rivals Apple. I love my Nexus S but the spell check would come up with some funky stuff sometimes. This new version (ICS) is perfect. Everything gets spelled correctly, it never guesses strange names (like going to spell GUESS and hitting GIU and my NexS spelling Guiseppe). It's making me think twice about it because the typing is soooo smooth, but, not being able to use FB or Google+ or Twitter properly makes it kind of hard for me to stay with this. Ontop of it all it just freezes up on occasion and the camera performs strange at times.
Check out the pics and if you have any questions you can always ask away and I'll give you the inside scoop and webpage links on how to root your phone. It's easier than the new iPhones. Trust me, I've had them both.