I've played about 5 games of dominion and lost all of them. Of course, that doesn't have much to do with this discussion, but I HAVE seen many flaws with it during my experience.
The first one is your speed, tanks, and durability. Champions like Teemo, Orianna, etc. can increase there speed by quite a bit. Thus, they are able to get to turrets faster and they are able to get to them faster. Leaving their defense and offense great. What I've noticed about the tanks is they have high cc or damage, leaving them as a threat even though they can almost not be killed. Creating the game much harder, yet more fun to play; but in Dominion, that statement is false. Tanks are practically USELESS within the fights on it. Due to the high pace that it goes, they will not be able to tank without any of their damage dying before they can get into the fight. They also can not hold the turret attacks. Tanking a turret in League of Legends is a big thing! It can cause you to win the game by doing it, but in Dominion, I didn't see that the tank held the aggression of the turret. Even though he had hit the enemy champion within range, I hit it after and ended up taking the aggression. I'm not sure it it's a bug, or it's meant to be that way, but that would leave tanks almost USELESS. Then durability comes next. It may fall under the discussion of tanks, but I don't really think so. Champions like Kayle, Tryndamere, etc. can cause themselves to become invulnerable. Thus, they are able to get into and out of combat without being touched. It is that way in every game, but in Dominion, it gives them a high advantage. It leaves them able to stay at the turret and continue capturing even though there are incoming enemies. They are also great at defending. You can not be hit while capturing, thus, you must kill the unit before capturing. You can't kill Tryndamere nor Kayle while in range of the turret due to their invulnerability, but it is also hard to get away due to the long range of the turret, and the slow that they can set; meaning they are way too durable to kill and they can kill you within seconds leaving escaping quite hard.
The biggest problem that I see within the game is creep farming. Riot may have said before that the amount of gold you get per sec will cover the creep farming, it's false. There are champions like Nasus and Veigar that will have a LOT of trouble with this due to the amount they rely on farming off of creeps. It also makes junglers a problem as well. They rely on having more money and levels due to the amount of minions they've slain early game. Well they can't do that in dominion due to the fact that they don't have many minions and NO neutral creeps.
I hope people get what I'm saying in this situation. I know many of you will say stuff like,"Don't pick those champions then," or maybe,"Dominion is awesome!". Well, I never said Dominion was bad, I just said that they have some flaws, and people really like playing farmers. I know my brother can't play any other champion BUT a farmer because he's done it so much. It prevents champions from being able to play the map making the team fall apart. This is a heavy team game, and if one champion does bad or leaves, they will have a very high chance of losing. Thank you =)