I played a game online, thought it was awesome, next thing i knew it's 10AM. Thank god i didn't have anything to do today! 
 
Love it so far, getting a lot of assists, not many kills and maining Ashe. 
 
also is master yi overpowered as shit or am i just really bad because i can't stand toe to toe with that guy no matter who's playing him.

 Welcome to League. :)
 
Master Yi is squishy, having said that, he is strong late game so shut him down early. (gank his ass)
 
Also, anything that disrupts melee characters works great against him. (Exhaust, Blind, Any kind of slow etc). 
 
If you've got any questions what so ever, you can add Vision in-game. I'm on the US servers. :)

I should get back on this game soon.  I play a mean Veigar, though unsure if he got nerfed as it has been a while.

They haven't made any changes to Veigar in the last 4 or 5 patches.
 
He got a small buff in 106.

I've been playing it pretty much daily with my friends while we're on skype. We're winning a lot, and it's a fucking blast. 
 
Master-Yi is insane if fed, but if you are two strong heroes you can take him out pretty easily if you stun him.

Welcome to LoL! 
 
Ya. Master Yi is super powerful in the late stages of a game or if he gets fed early. He can run away from or chase pretty much anybody, and when he has his gear set, he can wipe a whole team in a team fight, as long as he's not the one to initiate. 
 
Standing toe to toe with Yi is really hard because most Yi's build a combnation of attack speed, crit chance, and lifesteal. 
 
But like others have said, he's really squishy in the early game so try and get some ganks on him early to shut him down.