Green Man Festival, Glanusk Park, Crickhowell

Now you see them, now you don't, but that's magic

(JACK PLUNKETT / AP )

There has always been something magical about the Green Man Festival, but this year – for the first time since it started in 2003 – there was just a glimpse of something up its sleeve.

The spell was broken on arrival, when the rain that had collected in the plastic sheeting above the box-office "Press" window, decided to empty itself on my head. How the folks around me laughed, and, getting into the festival spirit, I laughed too – but the fever that I'd kept at bay all week was to magically reappear in a damp tent in a muddy field in the Brecon Beacons.

We are professional. We plough on (indeed, a plough would be handy). But what's this? Having timed our afternoon arrival to set up, eat and, you know, chill before Caitlin Rose's early evening appearance on the Green Man Pub stage, we hear the gorgeous "Own Side Now" wafting over from the main stage. We learn later that Mountain Man got held up on the way and Rose was asked to fill the slot, so anyone heading off to see her later will instead be treated to a disappearing act.

To complaints about the mud which no one can do anything about, add those about the programme (previously free) now costing £6. None of which would matter if the headliners were not also more Paul Daniels than Harry Houdini: Doves failing to take off and Flaming Lips, for all the pyrotechnics, unable to make their music match the visual stimuli.

Down the bill, some lesser names manage to pull something out of the hat: Sleepy Sun's psych-rock wig-outs are an otherworldy thrill; Egyptian Hip Hop are spellbinding, even if – at this stage – they are more apprentice than sorcerer; and the Unthanks' bewitching blend of folk and clog dancing gets young and old clapping along.

It is left to Joanna Newsom, Sunday night's headliner, to bring the event full circle. The act that took me to the Green Man in the first place back in 2004 has since smoothed those aspects of her voice that once divided opinion. Even the rain can't break her spell.

To conclude? Though the meh outweighed the magical by some distance, the UK's favourite boutique festival is not yet ready for its "now you see it, now you don't" moment.