The Mega 6.3 has a 6.3-inch, 720p display; 1.7GHz dual-core processor; 8-megapixel camera; and Android 4.2.2 Jelly Bean with Samsung's user interface.
Those are decent specs for a tablet of that size.
Could you imagine if Samsung tried to make a phone that big? That would truly be crazy. Like, holding a plate to your ear crazy.