I don't fully understand how it works. Let's say opponent has two 2/4 minions. Will they each attack each other consequently or there will be one fight between them?
How I understand it, is that they both attack random minions on the board. In this case they would attack each other end up both killing each other.
Lets assume that there are 4 x 1/4 minions, then I figure each of them will attack -> each of them will take one damage on attacking. Then it is random which minion they attack, in case 3 of them would attack all same minion, it would die. At the end there would be 2 x 1/3+ 1/2 + 1/0 (dead). So in this perspective, it is actually not even close to brawl. On the other hand it may end up on full board clear which brawl never does.
This is like the Swiss Army Knife of Board clears. It can be compared to almost any board clear in the game, but it all depends on the board state. It could be a cheaper Twisting Nether or a more expensive Unwilling Sacrifice. It could end up like Enter the Coliseum with 2 damaged minions or a Brawl that leaves 1 minion damaged. Obviously you want a controlled outcome, but you might not have that luxury in every game.