Flex Dashboard Vs. Shiny Dashboard

I would say that I have an intermediate R skill level with zero Shiny experience. I am interested in learning/gaining some dashboard experience. I am looking at both Flex Dashboard and Shiny Dashboard to get started. Would like the communities opinions as to where I should direct my attentions. Thoughts?

I think theres a rule of thumb that flexdashboard will help you with rmarkdown work, and shinydashboard with typical shiny web app stuff.