It is not pay to win at all. Sure the curves are not balanced. But that is not necessarily a bad thing.
It is possible to get all ingame items just by playing (and not even playing for that long compared to other games). A lot of players have done this.
All you need is a snail and maybe one faster curve like cube and rocket to be on par with the best players curve wise. If you are skilled you can even get to the leaderboard with a ghost. This game really is all about skill.