I've been working with Marketo for years now, and we've been through a Munchkin update or two, but this new update strikes me as one of the most significant changes that I've seen in fundamentals of how we work with Marketo.
For anyone that hasn't read the FAQ - Read it
I'm going to refrain from posting my own personal concerns at this point as I'd love to hear the community's thoughts on the matter without tainting it.
I have already shared my thoughts in another thread & will refrain from complaining over having my cheese moved.
If you haven't seen it already, there's a pretty lengthy discussion that has been going about this. May be worth checking out.