I played CS last night... it is alright. It would probably be more fun if you play with a team and can talk to each other. Team work is definitely required.
For $15.. it's about right, anymore or it'll seem very expensive as it does feel very PC-like game.
Is it worth $15? Maybe.
Never played CS back in the days it was popular, MW1 is my first 1st person shooter game.
Perhaps CS would be a good option to play if we are bored of MW3 and just in case Black Ops 2 is a flop.