I thought it was fun during a few pre-season games. It was kinda like how we used to play hockey in our streets, as kids... It was unorganized and messy but fast too. But the teams have now adapted to it to the point that it gets boring. Usually, the team that gets the puck first will do everything to keep control of it until they score. Whenever they need to change players, they will pass the puck to the goaltender who will wait for the new players to hit the ice. If they lose the puck, the chances a goal will be scored on the other end are so high, I'm not even surprised whenever it happens.
It became predictable really quickly.
And the goals aren't particularly exciting either since it's often the same scenario where the goaltender simply can't do anything about it.
I prefered it the "old" way: 4-on-4, then 1-on-1 shootout. At least there's more strategy during a 4-on-4 overtime.
3-on-3 seems to result in less shootouts too, since more goals are scored before the shootouts can happen. I love shootouts, they are always exciting and if you watch the game with a friend, you'll bet on who's going to score and who won't.
I think the whole 3-on-3 thing is being pushed down our throat because the TV stations don't like overtime. It means another program is getting delayed. Also, the coaches and GM's pretty much can't do anything about what happens during a shootout since it's all about one player Vs. a goalie. I bet they get new grey hair whenever there are shootouts so I understand why they wanted 3-on-3 to happen. Doesn't mean I like it, though.