I have it on steam . It's good fun, and like all pay to win games you don't actually need to buy anything to come out on top, the standard shotty is a beast.
Well yeah, most play to win games should work like that, but TF2 has a big arsenal of overpowered weapons so you either have to wait long time to get one or pay money for it.
Unless you play in a tournament like atmosphere (just the stock weapons) the game becomes unenjoyable after a time.
Besides the current TF2 is about trading You can wonder how TF2 traders can get new games by simply trading. My friend could get several games by spending no real money, just by trading.