I just received one of these from GotVapes.com. The battery stands about 1 mm shorter than a 1000 mah eGo pass-through. This battery however doesn't have a pass-thru. The build quality seems very good. The firing button is metal and doesn't feel lose. Rather than a button that lights up when pressed, there is an LED ring around the edge below the button. The power indicator at the bottom edge of the battery consists of four segments that indicate how much power is left with red LEDs. These are covered by a small plastic window. The LED ring at the top and power indicator light up simultaneously when pressing the firing button.
One thing I did notice was that unlike other eGo batteries, this battery only had two notches by the threading as opposed to the usual four. You might not be able to use these with certain atty's as the air hole might be covered up completely. Of course, you can screw on your atty onto the battery so that it lines up with one of the notches. I tried this battery with two different eGo-T tybe B atomizers and they weren't getting any air at all.
Vapor Production
I tested vapor production with a bud sapphire carto with a 100% PG 18mg nicotine e-liquid. By the way, screwing the carto completely onto the battery didn't seem to block air from getting into it, though your experiences may differ. The LED ring indicates which voltage the battery is currently set to. Red indicates 3.2V. Purple (really both blue and red LEDs on at the same time) indicate 3.7V. Blue indicates 4.2V. In order to change voltages all you have to do is press the firing button five times in a row quickly. At 3.2V the vapor was what I'd expect from the carto running on a standard battery -- a cool draw with a decent amount of vapor production. At 3.7V, vapor was slightly warmer and there was definitely more of it. At 4.2V it was much warmer but by no means uncomfortable. Vapor at 4.2V was much thicker and richer on exhale. Flavor was a bit more pronounced as well.
Overall, I like this battery a lot. I haven't yet had a chance to see how long this will actually last between charges, but at 900 mah it should last me most of the day. I love that there's a power indicator. I've never liked being surprised by a dead battery in the middle of a draw. Also, the bottom of this battery is flat unlike other non pass-thru batteries that have slightly rounded ends. Its completely stable when standing on its end. Vapor production is great at 4.2V. I usually don't vape 100% PG because, for me at least, it lacks that feeling of fullness in the mouth and throat that VG mixes give me. At 4.2V I get that feeling and it's just amazing.