I don't go along with the stereotype that Nas can't pick beats. Dude has made 100's of songs, heck include his features and he's prolly pushing a 1000. He's gonna have a few in there that not everyone is gonna feel.
But the vast majority of his stuff beat wise has always been tight.
Now having said that...
"Y'all can keep your weak beats from your corny producers..." Is one of the Most ironic opening lines to a song ever. That beat is horribly basic, just laughable. Too bad cuz Nas was dope on there, but I just couldn't get past that beat. Terrible.
But Em was at his peak then, even as simply a producer for what he did with lose yourself. It was a way for him to get Em on his album but without rapping, didn't wanna risk getting renegaded (not saying he would have).
But look at that same album, also has classic production all over it. Nas has way more dope beats than wack, especially when including a lot of his unreleased stuff.