Had my Android for a couple years now, original battery is still good. Took a business trip to Japan. Costs too much to call and not very compatible over there anyway. Left the phone in Airplane Mode the whole trip. Never had to charge it for the whole week. Got back to Tulsa with the battery indicator just starting to reach orange level.
I use it to store my music as well as phone functions. I can listen to music all day and still have plenty of battery in the evening. But if I do much broadcasting (GPS functions, continuous Internet access, etc.) the battery is almost dead by end of day.
I make sure to run the battery down into the red zone frequently before recharging, so that may be helping the endurance.