There are tuns of threads about the battery life on the TP here is my favorite:
http://forum.ppcgeeks.com/showthread.php?t=45060
Mostly because I rote it
but to answer your question I carry 3 batteries with me I will go through 2 every day and on days when i have a lot of calls I will use all 3. Just surfing and texting at home I get about 4 hours on a battery if I have Bluetooth turned off.