I've always felt Hero-deities and Quasi-deities were technically 'Half-gods'.
As to your template:
You may just want to say they are 10% taller.
If the god-parent was an evil deity would the child necessarily be beautiful? Perhaps higher charisma, but not necessarily beautiful.
If the god-parent were a deity of strength would it still only gain +6 to strength?
Some of the special qualities sime a bit extensive, but I am most curious of the sort of niche you saw this fitting into? With regards the Deities & Demigods book that is.
You could be falling into the same trap as the Celestial and Half-Celestial from the Monster Manual, wherein the latter is (for some reason?) the more powerful. Instead of Half-Celestial they should call it the Triple Celestial.
Similarly your Half-God template looks more powerful than some elements of true divinity. Although theres certainly nothing that suggests you have to abide by WotCs constraints.