I would love to not carry my charger when I board a plane from HI to CA. But if I play around web browsing on my old SP2 for an hour before take off, I'll already be 70% or less. Then I watch a movie for two hours, I wouldn't have much battery if at all. I really wish manufactures in general would quote battery life better."
Example: Get an average person who knows a bit about PC computers. Hand him the computer and say browse the internet/watch a movie/play an app or something. Then see how long the battery lasts. Get three or four people. And get an average. Now we know. But that ain't going to happen. They will run the test in a lab and see what's the best time doing the least amount of stuff that still looks like we're using the notebook gets.
Of course, let's say that MS does an honest mixed usage battery test, and says "you'll get 5 hours of battery life" and then HP or Dell says "12 hours" haha. What do you think MOST people will think?
Regardless, I just checked their website and they state "2 Hasta 9 horas de reproducción de vídeo." Sorry, local Spanish site came up. And it says it's 9 hours of video. I saw someone get around 8 hours of video testing, so I think this is completely doable and realistic. The thing is, we test video, downloading, browsing, commenting, painting, etc. It's NOT just sitting down and watching a show or movie for 8-9 hours straight, with no other apps or processes loaded into RAM. You know?