@Dstinct It is there to help that too, but it helps poorly on that since you actually need to leave both cards on top for the +2 to work.
Not that I think this will see vintage play. But if it does vintage always has SDT, jace, brainstorm and preordain to set the top card for the 0 ability.
Bolt isn't really played as much anymore, but it still pops up. So this is 6 mana to come into play out of bolt range. That aside Nissa's main problem is she can't protect herself and is just inferior in most of her abilities to existing planeswalkers. Jace lets you dig 3 deep and put 2 cards in your hand. Nissa only lets you see 2 deep. Narset works off of spells and puts them into your hand. Spells are still much more common and relevant in U decks than creatures ever will be.
And Chandra gives you creatures to attack with (though not with flying) without putting your lands at risk to STPS.
Its certainly an interesting card and at a glance its low CMC and the X seems to make it at least a consideration. But a closer examination shows this just doesn't do enough for vintage.