Originally Posted by _digital
I also purchased the Anker from Amazon. Since I do electronics for a living, to me the math for it lasting a lot longer just wasn't there. The shipped battery is speced at 1730 maH, and the Anker is 1900 (roughly 10% total capacity). That being said, if your existing battery is not performing up to spec (the capacity does degrade over time), you could see a significant decrease in battery depletion over time when in use. For my phone, I ran two specific tests, one using Netflix which not only uses the processor and display, but also the radio heavily, and one where I used resident games for an hour. I made sure the battery was fully charged (green and reading 99~100 percent) at the beginning of each test so as not to skew the results. The end result is that the difference between my existing battery and the new one was only 2% on the battery meter, with Netflix running it down substantially with both batteries. This confirmed that for a day when I use the phone heavily, I will only see a marginal gain in time.
The battery draw while in standby is obviously quite a bit lower, and if someone states they get a lot longer standby time, that would make sense. I charge mine every night and have no need to test that.
My suggestion would be to purchase this if you think your battery has lost capacity, but don't be surprised if your battery is relatively new and you purchase a 1900 maH battery and see only a marginal if any performance increase.