I bought this recently and have been using it just about a month.
After following the charge, deplete completely, then charge again cycle for three movements, I can happily say it works great!. The battery does make it a bit heavier and they do provide you with a new cover, but still no luck finding an actual cover that fits the phone completely yet. I can charge it at home before bed, and leave it on till the morning and have an 85% battery left. (I also have an app that automatically saves power by shutting things down on a timer, so that also helps. GOPOWER MASTER 2.5) Then I take it into the car and use my GPS along with Bluetooth for approx 1 & 1/2 hour drive and get to about 55-60%. Pretty dang good as before I had to charge in the car after only a half hour dropping to 50% battery
Metro originally sold me a clear gel cover for the unit pre extended battery. It still covers mostly, but is a bit short on the sides where the SD card sits. It does cover the top and bottom, so I use it for now as a precautionary measure until I find something better to protect the phone in general. @ 11.98, couldn't beat the price.
Hope this helps!