Just got the two battery & a charger today 4/20/2012
First, thanks for posting the info about this Anker battery. I ordered 2 batteries w the charger thru amazon for $13.99 plus $1.22 tax and free shipping with other purchases. The order arrived today, 4/20/2012, at 11:30 am. I put one of the batteries in the my Tmobile GS2 at 11:56 am and it shows 64%. Now, 12:20 pm, and after a few group texts, it drops 57%. So I don't know if it were good or not! Oh, I also use Easy Battery Saver app, too. So, will have to see how it goes. Will report back.
Now at 1:00 pm, dropped down to 48%, only group texts, nothing else. So from 11:56 AM to 1:00 PM, dropped from 64% to 48%.