Like I said, the nerf is better than nothing but I've been giving the whole Unleash The Hounds thing a lot of thought when playing. In my opinion, the card is, fundamentally, a broken card. Less than a week after it was buffed from 4 mana to 2 mana, the Meta shifted hard to Hunter dominating the game. Counters came and went. Hunter decks changed a bit. But ever since that change to 2 Mana, the entire Meta has revolved around Unleash The Hounds. Every deck that has been built since that buff has had to answer: "How do I play around UTH?" No other card has had that type of affect on the game and for that reason alone, the card needed to be changed.
Back when they nerfed cards like Novice Engineer and Shattered Sun Cleric nerf the reasoning was "everyone is playing this card so it should be nerfed." I didn't agree with a lot of those nerfs and I still don't really (but it's way too late to complain about those nerfs). But the impact that UTH has had on the game is just felt so much more. When building a deck, nobody asked "OK, will this deck be able to play around a first turn Novice Engineer?" But every deck since January has had to analyze UTH and the effect that it could have on the deck.
Finally Blizzard has stated that they want people to play Minions. The common perception is that you play around UTH by not playing minions. That completely goes against Blizzard's vision. Now there's a difference between over-extending and losing your board to a Mage's Flamestrike and automatically losing the game because you gave the Hunter additional resources by playing your own minions. The Mage is hitting a reset button with Flame Strike (and it might not even kill everything). However, UTH, when played right, acts as a board clear, board presence, card draw engine and direct damage. Yes it was a combo but that combo was extremely easy to assemble with card draws and mulligans. Of course there were times where both copies of UTH ended up at the bottom of the deck but even in that case, the opponent had to assume that UTH was a potential threat at all times and play accordingly.
Like I said, I'm still not convinced that 4 mana wasn't the correct cost in the first place. There was just such a knee jerk reaction from the original UTH nerf that very few people tried to give the new version a serious chance.