Media playback is unsupported on your device Media caption BBC 6 Music held a "listening party" for A Moon Shaped Pool on Sunday

Radiohead's ninth studio album, A Moon Shaped Pool, has been described as "stunning" and "a triumph" by critics.

The 11-track record was released on Sunday to digital retailers and streaming services - with the exception of Spotify, which has a turbulent relationship with the band.

It features several older songs, including a studio recording of True Love Waits, which dates back to 1995.

Reviews have focused on the "beautiful tunes" and "superb musicianship".

The orchestral arrangements, written by guitarist Jonny Greenwood, have won particular praise from critics.

"The pivotal newcomers are swelling strings and, most strikingly, a 13-person choir from the London Contemporary Orchestra in a shift that points to lead guitarist Jonny Greenwood's recent film score work for Paul Thomas Anderson," said Chris Barton in the LA Times.

"They seem as fascinated by sonic textures as they do by actual songwriting," agreed The Guardian's Alexis Petridis, "but it's not an album that feels lost in experimentation. The abundance of sonic intrigue is matched by the quantity of beautiful tunes."

Image copyright XL Recordings Image caption The album comes five year's after Radiohead's previous release, King Of Limbs

The ballad-heavy collection reveals "Radiohead at their least bloodthirsty and most accessible," argued Neil McCormick in The Telegraph - but that's not to suggest they've lost their ability to unnerve.

"Radiohead have always had a way with a lullaby," he explained. "Now they have produced an entire album of the kind of songs that could lull you into sleep but may give you nightmares."

"Grim tidings arrive amid gorgeous backdrops... Beauty is always laced with dread," concurred Jon Pareles in the New York Times, observing that Thom Yorke's lyrics were shot through with heartbreak, perhaps reflecting his "amicable" split from his partner, Rachel Owen, last year.

However, all but three of the songs pre-date the end of their relationship, noted the NME; which has led some fans to worry it is the band's swansong.

"With the album being so geared towards their audience's favourites, they're seeing it as a sign that this could be the end," said Rhian Daly. "But with Radiohead, who knows?"

Image copyright XL Recordings Image caption Two videos, including the Trumpton-themed Burn The Witch, preceded the album last week

"Closing with a song that has been knocking around for over 20 years may imply a lack of inspiration," acknowledged McCormick, referring to True Love Waits, "but actually I suspect Radiohead are a band with the vision and patience to wait for the right framework for this little masterpiece."

The song was originally a simple, acoustic ballad, says Jon Pareles, but it has changed beyond recognition on the new album.

"Instead of guitar chords, it starts with four repeating piano notes, a chord dissected and laid bare. The same piano figure sketches the song's other chords through the first verse. Gradually, more pianos are overdubbed: in rippling loops, low resonant tones and repeated chords, not so much filling out the arrangement as emanating alongside it, somewhere between harmonious and oblivious.

"Two decades later, its studio version testifies to what Radiohead's patient perfectionism can achieve."

Several critics observed that the album was difficult to assess on first listen. "So much happens in Glass Eyes and the Latin-flavoured dance that is Present Tense, among other performances, that one suspects the album will blossom with repeated listenings," wrote Jim Fusilli in the Wall Street Journal.

"Suffice it to say for now that on A Moon Shaped Pool Radiohead once again communicates complex human experience through superb musicianship, boundless creativity and unwillingness to settle for the ordinary."