The battery life is bad, but I'm not that surprised by it. Current phone/tablets achieve a lot of their battery longevity by throttling performance, this is something that is not really acceptable when your device is a games console first.
I can only imagine that if an iPad mini had to run a program as intensive as the upcoming Zelda appears to be that its battery life would also suffer.
The Switch GPU does clock down to 307MHz when undocked. In docked mode, it can run at 768MHz, about 2.5x faster. CPU and memory speeds are unaffected.
The built in screen is fairly low resolution so there are potentially fewer pixels to push when the Switch is undocked. It remains to be seen exactly how quality/performance will be affected by undocking.
