I love Backgrounds. Want to have a character who is a priest of some god but is a member of the Fighter class? Give him the Acolyte Background, and he's a priest, no Cleric class required. I have a character who is a Sorcerer-Priest of the God of Magic in my brother's homebrew setting, merely by giving him the Sorcerer class and the Acolyte background.
My brother just created a character for the Greyhawk campaign I will be starting soon, and opened up entire new worlds of possibility for the campaign by making him a Hexblade Priest of Wee Jas, by choosing the Warlock class and the Acolyte background. We removed all references to the "Raven Queen" in the Hexblade description and replaced them with Wee Jas (The Witch Queen) and came up with the idea that he belongs to a Sect within the Church of Wee Jas that believes that the "Hexblade Entity" (or whatever you'd like to call it) was created by, or is otherwise tied to, the Ruby Sorceress, meaning his Pact as a Warlock is indirectly a Pact with Wee Jas herself.
I think it's brilliant.
Backgrounds don't need to have any whiz-bang powers to make them important and significantly impactful to the character, just the campaign implications of what that Background means.