I don't think the free is much of a worry at all. Yes, there will be micro-transactions, though I feel that it will be similar to something more like Battlefield Heroes than something else in regards to the fact that yes, it could help you level up a tad quicker, and maybe give you hats, though it isn't much of a worry in that regard.
Micro-Transaction games have been gaining increasing popularity as they expand out of Asian MMOs and into other game types and styles from other places around the world. I quite like this because it's really a kick in the balls for big scary publishing companies like EA and Activision who are bullying smaller game developers to market their games at $100 and the second it is released, make a sequal instead of actually putting more work into improving and adding onto the actual game itself, something the publishers don't get any reward out of. If this succeeds then i'm sure that this game will continue to develop, maybe in a similar way to TF2, years after it has been released and prove to those smaller developers that they don't have to fit into the norm.
This is similar for other developers such as mojang, who from out of nowhere, created a huge game and said stuff you to the publishers and released it themselves. They're also going with the micro-transactions in their next game, scrolls, further showing the power of this new payment method.
I think that this whole phase of paying for games (either through indie developers or micro-transactions or other, outside the box ideas) is a positive step into a new way people not only pay for, but also play their games, the way that they personally want the game to be played.
