I get atleast 2 days and thats with a few hours of brosing with safari over wifi & abit of music playing on the ipod function.
For what is does battery life is great, i think once the novelty of it wears off i will get 4-5 days.
Are you signed up to o2 contract? or have you unlocked it?
Also to everyone if I dont unlock it and just use the o2 contract that comes with them can i still jailbreak???