Yeah the battery life is pretty insane. It's hard to fully describe to anyone who hasn't had an ARM laptop.
Any other laptop I've owned, including the glorious ~2015 MBP, was liable to either hit 2% battery or completely die if I left it unplugged overnight, which I sometimes do accidentally because I like to put on some boring YouTube playlist as I got to sleep.
With my M1 Macbook Air, I can accidentally leave it unplugged while playing YouTube videos all night, and I can wake up in the morning to find that it still has >90% battery left, sometimes even 95%.
Most importantly, it means not having to think about whether the airplane has power available when I fly. I can watch YouTube for a full 6 hour flight with no worries. I once played Halo CE Anniversary through Parallels on my mac during a flight and it lasted 3 hours before hitting maybe 10% battery remaining, which is pretty good considering that's Xbox 360 level graphics.