Let's take a look at what is the longest laptop battery. I'm going to look at some random tests, and see what they say.
I see, here, that one is supposed to last for nineteen hours (but it's not stated which that one is). Of course, it can do this only if something else in the computer's changed, as well (meaning, if the battery's great, but the laptop's just EATING power, it still won't last for that long). And this is the case, for this one. It has a really good way of managing its power; which includes something called all-day-battery.
Like Dell, HP's also into the race of producing the longest laptop battery. It's made the announcement that one of their batteries went for longer than twenty four hours. That particular batter's power lies in that it's just very capable (rather than/combined with the previous computer's power managing ability).
Were there other things, other than just pure raw-power, that helped the company break the twenty four hours barrier? Sure. As I mentioned, you have to do other things, than just have a "good battery", to have it last long. In this computer, the screen's made in a very energy-saving way, there's solid-state-drive-technology.

Those were just taken out of the blue - and might just have been rumours. Let's take a look at a real laptop-battery-test, to see what is the truth (or was, when the test was done, and for the batteries tested). I take a look at one examples, of batteries that were being tested - in this blog.laptopmag.com test - and see that it lasted just over ten hours. And that... really, is enough. When would you ever need a 24-hour-battery-life? Maybe if you're out in the desert, or in some other place where you can't recharge it - and therefore need to get as much done in a sitting - but, probably, in no other situation.
Actually, it seems that laptop's the test's winner, so let's go into what is good/bad with it (it got 4/5, by the way).
Bad: that it costs more than others, and that it's kind of noisy. What makes this laptop http://blog.laptopmag.com/long-lasting-laptops-to-help-cut-the-cord?slide=1#axzz14cu2RnYL good, besides the obvious fact - which is the battery-life - is that the keyboard's able to stand a lot of spilling, and that it provides comfort. The harddrive's fast and it boots quickly. The speaker-sound is good (meaning you won't have to buy an expensive external soundcard/headphones, to get good sound). Also, the anti-virus is convenient.