The GV-1 is an excellent external optical viewfinder, albeit a throwback to last century, for the Ricoh GR. The optics are crisp and large. The framelines -- there are two: 21mm and 28mm -- are easy to see in any light. The optical unit is slightly offset to the right of the hot shoe to ensure better fidelity with the lens's point of view.
The one warning I would offer is that its finish is rough metal. That is, there is no design concession made for comfort to the eye or protection of eyeglass wearers from lens scratching. If you wear glasses plan on taking time to place some gaffers tape around the eyepiece to protect your lenses from damage.