Carl Weese at The Online Photographer have reviewed the D-BG2 battery grip for pentax K10D digital SLR camera.
He likes the ability to quickly install or remove the grip depending on your shooting plans. Wants more juice and beter ergonomics with the heavy lenses - attach the grip within a seconds. Wants more portability and compactness - remove the grip and use one of the "pancake" lenses. "Same camera, two configurations"