I certainly have no complaints about my O3D. I certainly wouldn't say it was buggy (mine has frozen once in over 7 months - and that is when I was REALLY fiddling with it!). My last phone was a Blackberry and it froze at least twice a day! (that should put some contrast on what is reliable and what isn't!)
Looking at online specs, the Nexus S seems to have allot less features. Smaller screen, no HDMI output (which I use allot to show family pictures on my TV), less video codecs supported, no MicroSD port (it has higher internal storage but with no potential for expansion - where as the O3D can take a further 32GB if needed) and of course no 3D.
With all this extra tech it is likely that the O3D it will be a little bit heavier and thicker, but it is not a brick.
Some say the 3D thing is a fad, but you can take pictures in 3D and show them in 2D also. You can also convert 2D games to 3D 'on the fly', PLUS I have allot of faith in future 3D technology and can see me buying a 3D TV as my next TV. So to have past memories and video already in 3D will be a bonus.
I may sound a bit pro O3D (what do you expect from this forum!). Also, who is to say that ICS doesn't get leaked earlier? GB was.