I haven't read anything negative about battery life. I think the advertised life is 22 hours, but you can look it up.
Actual battery life in practice depends on a lot of variables. I see complaints about battery life with the Passport, which has an advertised battery life of 30 hours, and which in actual fact is indeed incredible in my experience. So when you read complaints you have to consider the user and the variables.
I wouldn't worry about battery life. Posted via BlackBerryForums.com Mobile
I have a Z10 and a 9810 on BES service and a 9700 on BIS and the only issue I had is allowing the battery to drain many times causing poor run times. The LI battery used in all cell phones not just a BB can have issues with battery's if they are allowed to drain or the apps on them constantly run causing the battery to drain fast. I would suggest a normal use should give the average user a full day of use or more.
My experience is 2 days on the Z10 and 9810 and longer on the 9700 which is used less during the day.