This addon will allow you to view your player over a length of time, such as differences in intellect/spell power/stamina ect.
It will also allow you to view your current item level (not the default UI item level), any changes you can make using stats you prefer, as well as gems and enchants in order to optimize your character. It will also track raid performance over a period of time for viewing if you are trying out a new spec or using different stats.
If using the tooltip feature the player will also be able to view item upgrades in a much easier manner compared to the guess and check method used by many players.