Its takes a good 2 - 3 months for the battery to get to its optimum power output! and people dont charge it right to start off, they need 15 to 20 hours charge for the first time.
Loads of ppl f**k their batteries themselves. Charge it for a long while before you use it and then only charge it up again when it is seriously low on battery. I know its inconvenient at times as you dont want to run the risk of phone dying but its best way for optimal battery life...or run it down by playing music/video etc and charge before you go.
And once charged, disconnect it from mains, so don't leave it on all night, only needs an hour of two. Think I'm going to go for gek award for longest N95 battery life when I get it lol