Your computer specs are perfectly fine for running it. You might not want to run it on completely maxed settings, but you can play it close to that with ease. I don't know where you read those reviews about the game. My roommate has it for xbox and I have it for PS3, we can't stop playing it... it's worth it, trust me.
If you don't like it you'll be the first that I know of.
Haha thanks Fatback for the video link.
It wont be your internet(unless it's horrible) and it wont be your computer specs. The game server itself will lag sometimes, like once every 10 games. Just because If a host lags out, it stops to find a new one instead of the whole game quitting, which is cool. And if someone is lagging, everyone's connection helps out to make the game run smoother. So, like all games, it will every now and then, but you don't have anything to worry about.