Well, its pretty much the same thing as on 5's, except there are only 2 people abusing a system which is sorta dysfunctional, and the rioters on the new TT forum appear to be far far far more active in community response.
Is there a way to somehow opt out of these games where you are the one person.
It also tends to cut down on who you can try out, and the general diversity of the game when 2 people spend their time attempting to tell people to play roles they've never touched.
To top it off, its liable I didn't even get a really negative report, but more along the lines of the community in the new 3's. I should not be forced into playing a tankydps/bruiser on every 3's game for the fear that the other 2 people will flame me just because I wanna try something suboptimal like an ADC. Isn't the point of the new 3's to make all roles viable to some extent? I realize that this is also partially a result of this map being a new release, and new players from 5's will come in, but it does not excuse people from acting like *******s in game.
TL;DR, disable reports for premade teams, or make sure there is some type of indicator when it comes to the in game screen or something. Also, 3's Community degrading.
I apologize if any of this seems unclear, and post if you want me to clarify something.

Game in question was
Morde, Garen, Vayne vs. Ez, Panth, Trundle.
I was the Vayne.
http://www.lolking.net/summoner/na/19544378#history
is the top game here.

There is a meta in TT just like in SR people are going to flame you/blame you if you pick outside of it in either map, I don't really think it's so much of a premade problem as a meta-breaking problem. I have seen adc's work in 3's but it's more of a high risk move to pick one.

What mustardstains said. You can't get punished by The Tribunal for breaking meta, so long as you act respectable (don't retaliate if they flame you). Hell, if they are flaming you harshly over it in game, you can report them for verbal abuse (pre-game chat doesn't get reported, unfortunately).