I'm guessing it was something like Uncharted 3 where you were constantly being flanked and charged at in a not so fair and fun way.
I'm just guessing though.
The A.I. in the Last of Us is overall pretty bad, but for some reason this is more noticeable at the start.
I remember in the first stealth encounter of all I was strangling a dude 3 feet away from another enemy, but since the other enemy was turned the other way he didn't even react...that was very immersion breaking. His friend was suffocating and fighting for his life right behind him and he just stood there.
I think the later encounters (except the last one) are fairly well designed and for some reason this kind of stuff was less noticeable, but still there. The encounters with infected are really cool as well.
Still loved the game to death. The game was more about atmosphere, for me anyway