Just ordered mine off eBay, $17.99 with free expedited shipping!
Extra battery life will be great, I am more excited about the added weight and thickness. I am a big guy with pretty big hands, sometimes it really feels to small and light. My wife has the Skyrocket and I hate how thin and light it is. Feels cheap and plastic-y.
I will report back with perfomance results. Currenly with CM9 and stock battery I get roughly 10-11 hours of medium use. If I could get a solid day (from waking up to going to bed) that would be awesome.