Compiz is a beautiful tool designed to please numerous users in terms of eyecandy windows, menus, interactions, effects, etc, a true desktop enhancements.
Small but eye-catching effects can easily be selected, especially by users who use dedicated applications, specialized in a particular set of effects.
Ubuntu Tweak brings various sets of configuration settings useful in various Ubuntu parts (like cleaning the "garbage", selecting font, choosing a particular theme, etc), incorporating a Compiz Settings dedicated page, too.
Transparent menus seem appealing for users used to a fancy desktop with effects, addition that can 1-click be selected via Ubuntu Tweak by navigating under
Ubuntu Tweak-->Tweaks-->Compiz Settings-->check Enable transparent menus