You're right. It's got great power management - dyntick is part of it, and sleeps the processor for short durations when it's not needed. Why halt the CPU when the power difference is so minimal? Few other systems have this implemented so well.

This also means it's easy to hack the thing to keep bluetooth and/or wifi live when closing the lid - and the impact on power consumption isn't all that high, unlike other devices that, if you prevent sleep, drain the battery really quickly.