I have two of them. One for Leica M and another for Leica R lenses.
They are well made, mostly all metal. They are solid extension tubes with a Nikon 1 bayonet at one end that uses the camera button to release it. On the other side is the respective mount with a latch to release the lens.
There is no electrical contact, so on my wife's V1 you need to set the camera to manual exposure and a set ISO. If you try to use even aperture priority, the camera will give an error and not fire. Also worth noting, there is no movie mode with these rings.
There will be no metering graph so you will have to use the aperture ring and use the toggle to change the shutter speed. You will need to use the LCD screen or an alternative metering method.
I have used my 16-21mm WATE up to 90mm with the Leica M ring. All of them focus to infinity so there is no issue there. I have read that there are some issues with the VC lenses.
For Leica R I've used my 100mm makro lens, 180mm f2, as well as my APO Telyt system up to 800mm. They all perform properly.
My bottom line, if you want to use Nikon F-mount lenses, especially AFS lenses get the Nikon adapter. Getting the information from the lens to the camera is worth the extra cost. If you have lenses from another system and want to use them on the Nikon 1 camera, it's worth the $20.
I've had them only a few days, so will have to get outside to test them better. It is pretty amazing to have a 2160mm f5.6 equivalent lens. The Leica M lenses mate very well with the Nikon 1 as they are small and generally faster than the Nikon lenses. Of course they are also very expensive.
Here is a shot with the 35mm f2 Leica-M lens. It is a nice portrait lens on the Nikon 1.
The second shot is a uncropped photo of a bird that I'm not quite happy with, but it's what I have at this point. This is a 560mm f4 lens. That is 1,512mm equiv.