I am considering buying a GPS GP-E2 unit to use with my 5DsR as I've found the data logging from my 7D II to be quite useful in EXIF and Google Maps.
I know that it is physically larger than the Nikon unit some of my travelling companions have been using but it has some advantages: it doesn't draw power from the camera battery as it uses an onboard AA cell and it doesn't require a USB cable if used with a body more recent than a 7D or 1DX I. The 1D II has GPS built in.
Can anyone tell me whether it is a serious piece of kit or just clunky bulky junk on top of my camera?