The battery was replaced in a repair service store (Iphone 5s). Actually, I think Battery Life is very accurate. I also used Ibackupbot to test the battery, and get more information and it showed 620 charge cycles, so it was clearly an used battery. So I went there to ask for a new battery. Now, the new battery shows 0% wear level in Battery Life, and zero charge cycles in Ibackupbot (even though I have completed a cycle), along with some other information:
CycleCount: 0
DesignCapacity: 1510 (Isn't too low?)
FullChargeCapacity: 1600
I don't really understand DesignCapacity and FullChargeCapacity.