The real good stuff about this move is that you get full access to things like swo and etb....that allows you to do logging and post-mortem analysis of how your code came to be at this place. It's a huge step forward for cortex-m to have this stuff available for free and a real game changer for ST.
The probes needed to support most of these features are cheap too ... A simple STLink or JLink is enough for basic output and, as far as I know, the stuff even supports JTrace for full fat streaming trace! I'm currently pestering them to support orbuculum and orbtrace cos that would give you trace output on a $25 adaptor board.
Dave