I've bought this to replace my older battery (1.5 year old) in my HTC. Fully charged but has the same capacity than the old original battery has. Is is not enough for a full day. Unfortunatelly not better than the old one.
Very good gadget in emergency situation if your mobile, ebook, ipad, etc. are out of power. Just connect it with built adaptor and charge. If it is fully charged has enough power to charge 2 to 3 times my phone.