My biggest fear about this model is that I will be limited in the gameplay elements I have available.
For instance, when the game comes out, I was really hoping to pay a flat fee so that all heroes/items are available. I don't care about hats and skins, those should cost exorbitant money to the player so valve can keep up their profitable business model.
If it's based on how "nice" a player is(however that's determined), I'll still have to play a few games before I can unlock items at a reasonable price. And I'll have to make sure I play support classes, help people out, buy wards, give compliments, and upvote other friendly people to increase my ranking (I'm guessing criteria here)
This being said, I've played the beta extensively. I am a friendly player, and I do help noobs. I did the same in TF2...so I'm sure this model will benefit me more than others, I just don't want to have limited content (or pay super high prices) when the game comes out.