Seastan posted a dwarf mining deck here: https://ringsdb.com/decklist/view/10311/everything-costs-1-ft-thorin-stonehelm-1.0
He built it up around the new Thorin Stonehelm hero (in the 2-player starter/collector's edition box), and gives him very high praise. Thorin does direct damage, 1 point of direct damage to be specific, after being declared as an attacker and discarding the top card of your deck. He swings for three, so with his ability he swings for an effective 4. With low-cost attachment, you can bring that to an effective 6 (Dwarrowdelf Axe). Seastan described him as 'there's no other hero like that' (meaning, swinging for such a high value with so little setup).
I have a different assessment, but rather than derail the comments section of his deck on ringsdb, I thought I'd post it here.
Thorin is a strong hero, but I would argue that his strongest asset is probably his low starting threat (9) and not his 'effective 4' attack and easy setup to reach an 'effective 6.' There are other options which can reach 4 to 6 attack as easily or more easily than Thorin, but their threat cost or ability cost might be a bit higher. Examples:
-Hero Beorn with Tactics Aragorn on your team. No card draw necessary; you're swinging for an effective 6 right out of the gate, with no cost associated with activating an ability. Or you're swinging for 9 if you combine the two of them. Beorn also has the added bonus of giving you an early-game solution for defense. The main'cost' of this setup is that it's a 2-hero combo, so that plans out a good deal of what else is going into your deck.
-Grimbeorn. With his ability, he's swinging for an effective 5 against most enemies from turn 1. Add a weapon (Dagger of Westernesse) and that's an effective 6 or 7 depending on the enemy's engagement cost. Main drawback is the resource cost to activate his ability (Thorin's 'discard from your deck' is much easier to pay), and his higher threat (11). Added bonus is that Grimbeorn can do his thing for any player on the table, since it activates through defense and he has Sentinel.
-Treebeard hero, with no setup. Obviously you need to include healing, but if we are looking for heroes who can reach a high attack value right from the start of the game, or with little setup, there you go. Very high threat though.
Anyway, that's all... I do like Thorin very much, but he's not unique in terms of raw power.