The feature/functional evaluation step builds upon the initial solution requirements exercise and the preliminary design proposal. In this step, you really put together the picture of required infrastructure and training that will be a foundation of your Unity deployment process.
If you don't do your homework thoroughly at this point, you're likely to run into serious issues during Day 2 support, as users begin to realize that they lack the knowledge or tools to perform the operations they're used to doing with their previous messaging system.
