The battery will not be as good as the older 'dumb' phones but when you consider what this little beauty can do then getting a day out of it and whacking it on charge while your pushing zzzz's isn't a huge issue (where it sits alongside my hubby's iphone which also needs charging nightly too)
I use mine loads, cos I am on here and another forum answering questions which will no doubt involve me firing up the phone and fiddling around til I can figure out an answer. I text quite a lot, I use twitter and facebook, sometimes browse and oh yes occaisionally I use it on a call! I normally go to be at night with between 25 and 45 % left on the battery.
The latest firmwares on the phone helped the battery life considerably. Doing simple stuff like not having wifi switched on permenantly, same with bluetooth, keeping the screen brightness down... mine is perfect between 20 and 30% brightness except for very bright sunshine when I do whack it up, make a huge difference to the battery.
I wouldn't worry hugely about the battery life. There are people with minimum usage that report 2.5 days. I haven't achieved it but then my usage is not exactly minimal.
Hope it helps!