I'm a little dubious about using batteries that are are supplied by other manufacturers as they are usually very cheap and poorly made.
However the Anker battery blew all my misconceptions out the water. The first thing you notice how well made it is, and looks like a high quality product and not like it's cheap counterparts.
I really haven't had problems with the original Samsung Galaxy S2 battery however being a mid to heavy user I needed a battery with extra capacity just to be on the safe side.
First of all the Anker battery fits very well and other owners will be pleased to know that it does not interfere with the cases that you use. The back cover of the Samsung Galaxy S2 fits as usual, enabling users to fit their case with no issues, unlike the official Samsung Galaxy S2 extended battery which costs three times as much!
Peformance wise, the battery certainly delivers, I put it through it's paces with heavier than usual 3G browsing and playing MP3's encoded at a high bit rate of 320 kps. I am pleased to say that from switching the phone on from 0600 hours and getting home at 2000 hours there was 53% battery left, which is extremely impressive!
For those looking for a replacement battery or even a higher capacity battery look no further than the Anker battery for the price and the performance it certainly delivers!