for 6k you can get shen and win a lot of games
Not if your team sucks. Though, I will say again: My 3v3 team is undefeated, except for 1 match where only one of us connected. Shen(me), Shaco, Zilean/Akali
If you play for KDA, than you might not want Shen, he doesn't have much killing power. But he does have some douchebag moves. Taunt(Shadow Dash) while an enemy is near a tower, Port(Stand United) into team fights, Taunt and run into your team (forcing enemies to follow). If you're good (I'm not) avoid a lot of incoming damage with Feint.
Though, if you are just starting pick Ryze. He's incredibly easy to play and extremely powerful against people who don't know how to counter him (the majority of players lower than level 10)
I really eed to get back in and play some more, but my one friend who played Shaco kinda stopped playing.