[bowmanb]

I love my Nexus S, but I'm running CyanogenMod. I highly recommend trying it, especially if you aren't happy.

http://wiki.cyanogenmod.org/w/Crespo_Info

http://wiki.cyanogenmod.org/w/Crespo4g_Info (4G)

[keeperofdakeys]

My Nexus S runs 4.3 happily, although a little laggy in some places, and not much multitasking. It would be more than usable though.