I've gone through three Mophies. Two were rendered useless by the crappy Micro-USB port on the side (one had the port pushed deep into the phone when trying to insert the plug one day, and the other had the port break loose because of vertical pressure on the cord--it's too easy to bump when it's plugged in), and the third appears to work in every way (plugs in fine, charges fine, flashes all four white LEDs fine) except it doesn't charge the phone when you put the phone inside (sometimes flicking the on/off switch will get it to start charging for a few minutes until an error comes up about charging not being supported with this accessory).

I really, really want to like the Mophie, but my track record with it is not positive. They could go a long way towards fixing the biggest issue (the poor positioning of the port) by moving the port to the bottom of the device (the LEDs can be moved, made smaller, or go away completely--they're too big and bright and annoying, anyway, when charging the phone in a dark room) and ideally switching to the much-more-robust standard iPhone connector. For now, it's just too fragile of an accessory to stand up to regular use.

Just my $.02.