I like the game and plan on buying it, but it is pay to win. If two people play the same amount of time and one of those people buys credits with real money, that person has the advantage. That is the very idea of pay to win. You get an advantage over someone else by paying real money. Now, is it as bad as a game that you can buy a weapon that only real world money can buy and that is much stronger than anything else in the game? No it is not. But hardly any game goes that far.
The only way it would not be pay to win would be if everything you bought was cosmetic only (like GW2 or WOW). That is not the case. You can buy in game money that can buy you anything you want.