Quite frankly, probably the best possible option for a Gunslinger in 5e!
I am actually not using it for a Fighter, but, rather a Paladin's Sacred Oath.
I have a player in a game set in Greyhawk where there's a hero-deity who's renown for using firearms. And, I think this works rather awesomely for it!
Especially when paired with the "Firearms Specialst" feat available on DnD Beyond (and other game-mechanic resources), it gives the player plenty of options for the kind of customization they want to reflect in their particular gunslinger.
And there's enough balance that it doesn't disturb the game, even with strong things like adding extra damage dice with the possibility of misfiring and exploding one's gun.
I rather like using it in addition to the Rennaisance Firearms from the DMG.
It makes for even more interesting balance when there's loading guns with no misfire chance, as well as reloading guns with misfire.
Many congratulations, and thanks, to Matt Mercer.