Reading through the most up-to-date SRD (01-01-18) for Cortex Prime I'm really impressed. +Cam Banks has done an amazing job creating a core tool box that can accommodate a lot of styles of play.
I was someone who played the original sovereign stone and loved classic cortex. When Heroic came out in Marvel I didn't get it. I didn't get the abstract nature. It took me a while to 'get' the system. Once I did I really liked it. Some incarnations of Plus took me a while to warm up to.
This tool box approach allows for a mix and match of different options from all the past application of Cortex, as well as some new levers to push and pull to get new effects and styles of play. I love the idea that the system can bend and stretch to be what best facilitates the fiction and action. I'm really looking forward to the finished product.