Breath is an amazing 1 point skill, I use it literally every fight.
I didn't do much with fire spells until about level 14 or so, until then I was reliant on the Prince to drop ignite targets or barrels, clear surfaces, etc.
As for resistance wise, it's a rather nice boon. I personally liked it quite a bit, it helped make him a bit tankier, especially since I used him as a frontline damage dealer with some utility geomancer spells for armor restoration.
