I've had this camera for awhile (and also the GR). Still haven't found anything to replace it. Ming Thein's reviews are spot on - both are equal in different use. Now that price is no longer a factor (used Coolpix A's are cheaper than GRs), the decision is harder.
Images: Both have wonderfully sharp lenses - better than most 28mm DSLR lenses. You can't tell their images apart.
The GR has probably the worst OOC color profile I've seen in awhile. It's not a tragedy, but (red) needs work in post. But, its B&W is simply magical, to the point that I'd buy the GR just for B&W - it's THAT good. Build quality of the camera is not as good as the Nikon.
If you're satisfied with how Nikon DSLRs render color (I do), you'll find it's the same in the Coolpix A. Very little, if any post work is needed. B&W comes out more contrasty than the GR, same as from any of Nikon's DSLRs. It's nice, but not magical and I usually do some post work to improve it.
Operation: The GR is a bit snappier in use. I like the 'snap' mode a lot. But, if you use AF-ON for focusing (which I do for my DSLRs) , the Coolpix is just as fast. They're both pretty similar in speed of operation.
What I do like is setting up the Nikon. Although I'm not fond of Nikon menu-logy, the Coolpix is consistent with my other Nikons. I set up AF-ON, etc just like my DSLRs.
The GR has some better menu features (and some that are just as weird as the Nikon's), but the disadvantage to me is simply that it is 'different'. I hate having to relearn a menu every time I pick up a camera after a month or so.
I often carry the DSLR with a tele and the Coolpix for wide.
So, If you are a Nikon shooter, the Coolpix A is more practical. But, I'd get the GR simply for it's wonderful B&W.