On my original S4, I was getting 3 hours of screen time if I was LUCKY on a full charge. I got a replacement and am at 40% after 3 hours of screen time. Also, there is no lag on this unit, while my original one had noticeable lag. Very happy.
Yea, after receiving my S4, I'm irritated about how people say there is lag, either they have a defective unit, (which is a production issue non the less) or they just don't even own one and just say it to bash it. I love the battery, don't have any power saving crap on, all my cool little "gimmicks" (/end sarcasm) that i want on, and it last me all day and then some change.