How is the iPhone 4 battery life with the most recent updates?

Someone is offering to sell me their white iPhone 4 with 16gb of memory for 200. I need a new phone that I can depend on. How long will the battery last?

Added (1). 8-10 hours on STANDBY… That is not acceptable.

The iphone does have an above average battery life if you descesion for a new phone is massively based on battery life then you should go with some of the newer samsung phones like the S3 and Note, also nexus other options you could look at is a portable battery charger where, you charge it at home and when your battery runs down you could simply charge your phone with it on the move.here's the link for a good one.
http://www.google.co.uk/...exp=chrome, mod%3D16&um=1&ie=UTF-8&tbm=shop&cid=10074811543498481328&sa=X&ei=K7YiUJ7sBqaH0AXYlYCwDA&ved=0CHsQ8gIwAA

The iphone 4 on 5.1.1 has a great battery life, almost twice the amount the 4s has on the same firmware.

It depends on what applications are running. If it is jailbroken or not.mostly average battery life with a 2nd hand phone approximately 8 - 10 hours stand by.

Apple claims the new phone can outlast its predecessor by an hour in Internet use, two hours in talk time, and 10 hours of audio playback. Both the iPhone 3GS and iPhone 4 claim to hold enough juice to play up to 10 hours of video, and can last up to 300 hours in standby mode.