Been playing with it since yesterday as well on my HTC One.
Like it so far, like the idea of the activities changing during the day. Not sure how it's controled though. Today ie, I set it to Work, and when checking my phone later on, it was set on Home... don't know why.
Of course the custom side of it is quite limited, I assumed it will be better with later versions.
HTC One (M7)
Nexus 7 (2nd Gen)