Away from its charger for 4 days of light to medium usage, Shion is only down to 45% charge–I think it’s fairly safe to say the M2 has good battery life.
Makes me recall my first laptop, whose Sempron would generally reach 2 hours and 30 to 50 minutes if one was lucky. At the time, that actually wasn’t bad for an x86 laptop, never mind the third cheapest at Best Buy. It was a machine best used with a charger except for short spurts of being on battery, regardless of system load.
For the most part, I pretty much forget that my MacBook Air even has a battery.