Check this video out. Team Fortress video
Its good fun. There is no one single character that dominates - all of them have various weaknesses.
The one I'm good at is the demoman - who can throw explosives and place charges hidden behind walls to booby trap an unsuspecting enemy.
But the character that seems most interesting is the spy. Click on the link below.
Spy: Sneaky, Subversive, all round bad guy
The game is well designed. It feels like being in a Pixar movie! "The Incredibles". The funny Eastern European style music, the cutish 1950s props, and the multiple amusing taunts you can use with the individual characters.
But enough with my boring review. Play the game!!!