A non-scientific observation, but when the picture I had as my wallpaper disappeared (the Sound from the Outer Banks, NC), I tried one of the HTC vivid blue sky wallpapers. Battery percentage (using Circle Battery Widget) dropped like a rock. Now I understand why so many complained about battery life. Light user, and couldn't make it through the day on a single charge as I could with the old wallpaper. After a couple of days with that frustration, I switched to a darker HTC wallpaper (Polka dots with a lot of black background), and could easily see the difference with the battery holding up. Since the display uses ten times more power than any of the apps I'm using, the intensity of the colors in the display makes a big difference in battery life. Most of the stuff I've read about conserving battery power focus on minimizing brightness in addition to turning off power hungry apps. I think the intensity of the colors (especially the blues) in the wallpaper causes a significant drain on the battery.