I think the C-Stick is the worst inclusion in Melee by far. However, I understand why they added it in. The game grew so complicated that it was hard to master all the techniques so they created a dumbed down cheat with the C-stick.
Although it sucks, after my friends found that out, they wanted to play the game again. It allowed them to have even ground with me...because I never use that.
The best inclusion for Melee is that Charge Smash Attacks, I thought those were definately awesome, but with the speed of the game, AND C-Smashes they were made more or less useless.
You know the C-stick Smashes wouldn't have been that bad if they were made to be like 1/2 the power of a regular Smash. That way they become a means to use a Smash in a tight spot, but it isn't the end all means to Smash hit your opponents.