To really understand the scope of power that these eyes have, one has to look at the unique abilities of the known Mangekyou users in Naruto. Itachi's Mangekyou Sharingan posesses two abilities ...

The Hyuuga eye is depicted as being entirely white and becomes strained ... Perhaps the most famous Naruto ninja eye technique, the Sharingan is exclusive to the Uchihas but has been stolen ...