it definitely extends the life of my phone.  It was getting to the point that my battery was going dead 5 hours after I got up in the morning. I had to carry a spare battery or charge cable.  With this battery, it lasts from when I get up until I go to bed (and still sitting at 30 to 40%.  I am a heavy phone user whether it be surfing the net, listening to streaming music or playing games.  This battery definitely works.