I've tested battery life. Usually, I play some, write down how long I play, take a break, and comeback. Not this dude.
YouTube user Kurekureyon filmed himself playing the PS Vita and the Nintendo 3DS non-stop. Only occasionally does his hand leave the frame for what, I'm assuming, is bathroom breaks -- or coming up for gasps of air.
Above the PS Vita and the 3DS is a timer so you can see exactly how long each system's battery life lasted.
The PS Vita had its wireless set to flight mode, brightness at minimum and volume muted. The 3DS had its wireless switched off, brightness set to one, power-saving mode on, volume at minimum and the 3D effect off.
Granted, the test lasted around four-to-five hours for each handheld -- hardly impressive by marathon gaming standards. That is, until you consider that Kurekureyon was doing time trials racing game in F1 2011. The same circuit. For over four hours. Round and round and round. Madness.