Yep, I love them.
However, they are vastly more complex & subtle than the simple AVRs and PICs...
I'm currently working on a project using the MSP430FR5969 in ultra-low-power mode - a CR2032 will power this thing for 2 years...
Everything, and I mean EVERYTHING, has to be carefully considered - a simple slip and suddenly you've "only" got 1 year, not two...
Mind you, the power analysis, the EnergyTrace++ stuff that's built into the Launchpads, is insanely useful - I can see on an instruction level where uWatts are going. Bonkers.
Nick