I have found this to be a fine product. It charges two batteries at the same time. It charges a battery way faster than charging the one thru the camera and its a great way to keep the charge topped off. The Re-fuel battery that comes with this product works fine. It has about the same battery life as my GoPro battery. The charger is compact with the same form factor as a GoPro charger and fits in my GoPro case where a standard GoPro charger would fit.
So what's the one missing thing? A wall charger plug. It comes with a charger dock and a Micro USB charger cable. No wall charger. it can use a standard USB plug to charge the batteries but a stand alone 2 amp min (3 amp recommended) wall charger work best. Using a 3 amp wall charger really makes this product work great in terms of fast charging and if it were supplied, I'd give it a full 5 stars. Other than that, it's a good buy. It's cheaper than a GoPro brand and it's fully compatible.