your wrong, the s4 is technically an 8 core, just cause its 4+4 doesnt mean nothing, its still 8 cores working at different times, giving the other a rest, while a quad core their isn't a rest, its always being used up on certain power hungry apps.

and the s4 is more powerful than xperia z and htc one, what are you smoking?

But there will be no instance when more than 4 cores working at the same time. So, it's technically Quad Core! The lower clocked 4 cores are to save power unlike with other phones where the same 4 cores do everything! Samsung is trying to show that this solution will save power and equipped the S4 with a mid range battery unlike the beefier ones in Xperia Z.

the only reason Samsung use it in S4 is because they want to promote it so other people will use it over other manufacturers as they have just recently lost their biggest consumer, Apple!