Joni’s odd and beautiful open tunings are what set her apart. The way she combined these unusual chords with her unique soprano voice hadn’t been heard before or since. Blue is undisputedly Joni at her peak . Mitchell had become hugely influential to the likes of Led Zeppelin. Jimmy Page certainly made use of different tunings like on my favorite acoustic song of all time ‘Thats The Way’ on Led Zeppelin 3.

Jason Ankeny at Allmusic: Sad, spare, and beautiful, Blue is the quintessential confessional singer/songwriter album. Forthright and poetic, Joni Mitchell's songs are raw nerves, tales of love and loss (two words with relative meaning here) etched with stunning complexity; even tracks like "All I Want," "My Old Man," and "Carey" -- the brightest, most hopeful moments on the record -- are darkened by bittersweet moments of sorrow and loneliness. At the same time that songs like "Little Green" (about a child given up for adoption) and the title cut (a hymn to salvation supposedly penned for James Taylor) raise the stakes of confessional folk-pop to new levels of honesty and openness, Mitchell's music moves beyond the constraints of acoustic folk into more intricate and diverse territory, setting the stage for the experimentation of her later work. Unrivaled in its intensity and insight, Blue remains a watershed.

A review on Allmusic from Gibran Guerrero: Words cannot express the beauty of Blue. The shear passion and grief of Joni is superlative, and of course rather depressing. In fact, to this day: I have yet to find another album of equal soul. Preambles aside, Blue is an album of passion (A Case of You), love (California), insecurity (My Old Man), loneliness(All I Want). Acoustic for the most part, it consists of Joni's guitar and ethereal voice on occasion embellish by piano.

It's important to emphasize, the power lies in the lyrics. Expressing true emotion in events all too familiar for lovers and loners alike. All pretense of comprehension by the listener is forgotten by Joni, she only wants to feel and express her point of view. Far beyond its contemporary counterparts (Sweet Baby James, Pearl, Tapestry, etc.) the latter still won best album of the year. Still, Blue needs no recognition, because since June, 1971. It's already a timeless masterpiece!

Jenn Pelly at LA Times writes: Joni Mitchell was, as ever, in a philosophical mood. During the first print interview she gave following the 1971 release of her fourth album and masterpiece, “Blue,” she wondered, like she did in so many of her songs, whether it is actually possible to be both fulfilled and free. “Freedom ... implies always the search for fulfillment, which sometimes is more exciting than the fulfillment,” she mused in Sounds magazine. She mentioned her soul-journeying friends — which included the Laurel Canyon rockers who helped inspire her to shake off what little was left of her folk dust, embrace her own sturdy rhythm and delightfully proclaim, “I want to wreck my stockings in some jukebox dive” — who would come to her and say “they FOUND IT!” Two weeks later, they’d be unsatisfied. “Because they’ve come to enjoy the quest so much,” she said. “They’ve found it — then what?”

Could there be another way to regard the very nature of fulfillment? “I don’t think it necessarily means trading the searching,” Mitchell added.

Such was the restless dream of “Blue.” Mitchell sang herself into motion. She honored emotions as sources of knowledge. A lover of painting and jazz — of Miles Davis and Picasso, both of whom had their “Blue” periods too — she knew the potency of tone: of finding the correct register of a feeling. She twisted the knobs of the guitar until they sounded as inquisitive as she felt, and within her suspended chords, which she called “chords of inquiry,” she spoke straight to us. She wrote, in a possible nod to Nietzsche (after whom she named her cat), of her very blood. And as her words enacted a kind of emotional ekphrasis, getting to the core of her desires through precise details, her music itself — her prismatic piano playing, her narrative harmonies and the liminal charge of her dulcimer — told “Blue‘s” vagabond stories too: skating on a river, alone at sea, swaying with an unfamiliar breeze. “I was used to being the whole orchestra,” she would later note. Her voice conducted: bringing light to “California” or indignation to “hate” or wings to “fly.” Mitchell confronted her own complexity and put it into every note.