I like the 3-9X magnification for deer hunting, especially if you must spot antlers. Sometimes it's hard to see antlers in the woods in low light, so even if you normally leave the scope on 4X and identify a deer, but need more power to see antlers, it's quicker to do so with the scope than switching to binoculars.
(That said, someone will say it's not safe to use a scope to spot deer, but I'm saying that you've already spotted the deer, just need to identify it's an antlered deer.)
On the other side, the 9x power makes sighting-in easier and somewhat more accurate to sight-in the rifle.
Yes, 3-9X scopes are a bit big and heavy for .30-30s, but your dad got it for you and it's entirely usable. Besides, some day you may want to buy a bolt-action rifle in a more powerful cartridge, like a .270 or .30-06, which would extend your in-zero range.
“God save us from people who mean well.”
― Vikram Seth