YAML is a step forward, but I wish that Amazon would give up on CloudFormation. It seems like it isn't a templating system so much as a bad programming language in the making.
Simplified substitutions alone are a much needed upgrade. Writing Fn::joins everywhere was not only error prone, but also time consuming and confusing.
Very excited to play with these new updates. They were much needed! It'll be nice to get rid of the duplicated logic between stacks. Also, comments!