Since the Android Lollipop release, many legacy device owners are now "jelly" about the new Material Design look that's been spreading like a disease these days. If you're one of them, don't worry, there's still hope! It's called MonsterUI.
MonsterUI uses the well-known Xposed Framework, so it's really easy to use it.
For those that don't know what Xposed is, take a look here.
To enable MonsterUI, simply install the app, enable the Xposed module and reboot.
(Module should work on ICS,JB and KitKat).
Download MonsterUI (official thread, find more information here)