Since they made it free and added a thousand new items, there are vastly more new (less skilled) players, many games are spammed in both text and voice chat with offers to trade, and every game is a circus act of ridiculous hats.
With the exception of private clan servers, there's really no way to make sure you're joining a game with focused and skillful players.
* The hats break the usability of the game: characters used to have very easily distinguished silhouettes. Now it is harder to tell what is going on in the game.
* The hats visually and thematically damage a game that once had very strong art-direction.
* The variations in weapons makes the game harder for them to balance and harder for the player to find an optimal strategy.
* Allowing players to individualize their avatar encourages people to devalue the team aspects of the game.
It's still fun, but I want to play in classic mode.
Other than the (rather common) offers of trade from people wanting my earbuds [1], I'm finding that I'm coming across players who are as skilled or more skilled than I am. I'm actually learning how to better play the game.
My enjoyment of the game has increased since TF2 went free to play.
[1] http://www.teamfortress.com/macupdate/earbuds/ My response to offers of trade for my earbuds is to ask for $600 in return, which is about the cost of a new mac mini.