As for general battery life, based on these figures you'll get somewhere between 2 hours and 45 minutes to 3 hours and 15 minutes playing Breath of the Wild, depending on the settings you use.
http://www.trustedreviews.com/news/nintendo-switch-battery-l...
To the GP, Nintendo products have this effect on people. They're different enough that people don't know what to expect. You'll find similar sentiments about the Wii U (especially from Nintendo fans - the next Mario/Zelda/SSB is gonna put it over the top!).
I'm interested in wait and see. The hardware is mediocre even though the form factor is great. They really have to get more games out before the holiday season, though, and where they are at they're competing with both mobile devices and consoles. Parents have to justify spending $300 on this + full priced games against more games and better experiences on other consoles (MS IS launching a 4k console, too) and cheaper (much cheaper) games on mobile devices that aren't restricted to gaming. They're in a no man's land of markets where they compete with everyone (for good and bad).
....though it'll probably sell like hotcakes.