One of the best synopsis of what changed is here - http://www.imaging-resource.com/PRODS/ricoh-gr-ii/ricoh-gr-iiA.HTM
Scroll down to "What's been changed"
Wireless connectivity: Both for file transfer AND remote control of the camera.
Wireless flash support
Raw file burst depth: Ten raw frames
White Balance: Color Temperature Enhancement mode
Top shutter speed wide-open: Maximum shutter speed of 1/2,500 second at f/2.8, up from the 1/2,000 second. The top shutter speed at f/5.6 or smaller remains 1/4,000 second
More effects modes
Interval Composite shooting: Now also save in raw mode
In-camera raw processing
Better image review for raw files
Improved battery life
MOVIE RELATED ENHANCEMENTS (separated as many stills users don't care for movie stuff)
Autofocus during movie capture
Exposure compensation during movie capture
Creative effects during movie capture
So for me IF buying a GR for the first time I would opt for a GR II.
I would bet they have improved some manufacturing processes that won't be mentioned.
The extra cost extrapolated over time is not much.
Each to their own decision which may mean not buying anything.