It's no worse than cm10 or cm9.
I kind of like google now's functionality, so I am dealing with some crap battery life issues. I thought it was really laggy, but I disabled all the animations and transitions and it is snappy. I am trying to find a good kernel for it. i have no idea where the one I have came from, but it doesn't apprently support overclocking. It is 3.0.56.
I don't think that googlesphere is supported. I am using the release from 20130304 M2
One cool thing is I completely wiped everything this time and it automatically restored most of my apps with no intervention from me. I have titanium backup and did restore data to some, but not all apps. I didn't care about text messages, so I just let them go. The only thing I lost was a couple tasker profiles. I had one that took a pic by pressing an icon on my home screen. It doesn't open the camera app. There was another one that took a pic when I texted it a phrase, but that one is gone too.