Only a Sith deals in absolutes... (bwahahahaha..... I'm just completely poking the bear....) Look - academically - I would agree - Narration is often a tool poorly used to make up for poor storytelling.... but I gotta agree with his Ferris Bueller reference.... I don't think "narration" (if you could really call it that) hurts the film at all. I think it proved a fun, inclusive way of bringing you in on the whole adventure. I dunno - I don't have super strong feelings about it. Narration usually sucks... but I don't mind it on a rare occasion, in the right way.ALWAYS
Ferris Bueller doesn't narrate. He breaks the 4th wall. That's a whole 'nuther thing with a tradition going back to Seneca. Characters breaking the 4th wall (a term that goes back to Moliere) occupy an entirely different purpose than narration, which started with the Chorus. It's also a whole 'nuther can of worms in that the minute you start breaking the 4th wall you're delving into metafiction, for better or worse. Voiceover, on the other hand, is a narrative shortcut.
He's providing asides and insights. It's much in line with what John Hughes did in Breakfast Club - he had Anthony Michael Hall deliver a greek chorus like intro and outtro to cast the players as larger representatives of society. It's very much a "and these children that you spit on as they try to change the world" approach. None of what follows is relevant to the plot. It's all an aside which exists solely to increase our affinity for Ferris.