Microsoft Band SDK Release and Band Studio Introduction
channel9.msdn.com
channel9.msdn.com
Very exciting to be able to develop my own applications for it now!
It was only one day, but I left pretty confident in the data.
I have some weird heart issues and it can have trouble with that as well. If it's not set to track an exercise, it's frequently reading 10-15 bpm lower than my actual heart rate.
They can't give you usage numbers when there is no significant user base, and they don't want to discourage you from writing software for it by providing you with the knowledge you will make no profit from it. :P