Heroes Brawl is a new game mode that's added to the game on October 18. It is about breaking all the conventional rules of the game and I've been playing with it for a while on the PTR and here's a personal review based on my observation.
A Big Time Saver
Two rounds need to be won for your team to win the brawl. Each round takes only 5 minutes.
Regardless of which Hero you own, at the pick screen, you can choose from three randomly shuffle-picked Heroes that you will be playing every round.
Different modifiers affect the Brawl. There's a small chance that all friends & enemies will be the same Hero, such as 5vs5 Nova, Zeratul, Alarak or even Sgt. Hammer. Then there's an additional chance for teams to have the same Hero twice.
Talents & Heroics
This is where fun starts! Your Hero will have no talents, the only thing you'll pick is your Heroic Ability. I don' tknow to what extend this is balanced if all Heroes have no talents and another thing I don't like is that there's an unfair advantage with Heroic Abilities. Some are on extremely short cooldown (several seconds) and some are on very long cooldowns (even two minutes). I understand that some are more powerful than others but two minutes is simply too long.
The brawl maps are mostly single-lane Arenas with different objectives. The bad thing is they aren't on any rotation, so the map changes only weekly. Hopefully this changes in a future update as it's a little boring. At the moment, we've got Punisher's Arena up. To quickly sum up, Hero kills give +4 points, Punisher kills award +10 points. The first team to reach 100 points wins the round. Punishers randomly attack either players or one another.
Participating in 3 Brawls weekly awards 1,000 Gold and a Portrait, which is great and it doesn't take a lot of your time!
I think Heroes Brawl is a much welcome game mode as it's an absolutely great means of rest and fun from the conventional (Ranked, Quick Match) modes. It has a nice rewards as you can't complain about free 1,000 Gold every week. Another thing is you don't need to own a Hero to try him out outside of "Try Mode" and in the end it's all about fun! You don't have to do any strategies, you just go and kill your enemies. It doesn't really matter if you win or lose, just have fun.
I'd give the game mode a 8/10. I've subtracted two points, because I hate the fact that only a single map can be played at a time and not all Heroes are available in the mode yet, e.g. Abathur.