If you haven't already been spoiled within an inch of your life for Deep Breath, Guest reporter Tony Fyler has a spoiler-free review, after watching the Cardiff Screening.

When David Tennant regenerated into Matt Smith, it ushered in the ‘fairy tale’ era of Doctor Who. Wibbly-wobbliness went into overdrive, and the grownier-uppier section of Who fandom groaned, as the whipper-snapper in his grandad’s clothes gave us a bandy-legged, drunken giraffe of a Time Lord, with occasional snaps of old-man rage and frequent over-emoting.

Within the first five minutes of his screen time as the Time Lord, Peter Capaldi makes one thing abundantly, Tuckerishly clear: The fairy tale’s over. They didn't all live happily ever after.

The tone of the show has completely changed. This is a hardball Doctor – not grim particularly, but also not caring if he comes off that way. Certainly, there’s a ramping up of the Sherlock factor here. If the Eleventh Doctor’s ‘Thing In Progress’ style sometimes made it seem like his cleverness was mostly in his improvisational skills, Twelve goes out of his way to let you know he’s the cleverest person in this room. In fact he’s the cleverest person in any room you're ever likely to see – got that? Good; moving on.

He plays the post-regenerative story arc with a straighter bat than either of his recent predecessors – he does get put to bed, Tennant-style, in this story, but whereas Old Magic Sideburns was content to nap his way through all but the last ten minutes of his first story, the Old Man is up and at them within five minutes of going to sleep – and for fans of Jon Pertwee, there’s a punch-the-air sequence that brings back distinct sensations of the Action Hero Doctor. What’s more, he just gets stronger and clearer and more in control of his faculties from roughly halfway through the episode, after some great dark, semi-despairing philosophical moments that also include one of the episode’s signature comic monologues. Once that’s over with, you pretty much get 100% proof Capaldi Doctor right to the end.

And what is ‘Capaldi Doctor’? Bold, adventurous, assured, gritty, Sherlock-smart, personally vulnerable, witty (rather than funny) and something beyond mesmeric. Whenever he’s on screen, if you're looking anywhere else, you're missing the point.

Which is perhaps as well, because the actual storyline of Deep Breath could be considered to be thin on the ground. There’s a re-trodden set of villains from a previous episode, though they do get their storyline deepened and are rather gorgeously realised. The plot they have is moderately absurd, but then moderate absurdity is rather their stock-in trade. The delicious dark Moffatt twist, both times, being that people caught in the wave of their absurdity die. This time, there’s a properly Whovian stab against organised religion in the sub-text, which given that Moffatt’s had warrior priests, headless monks and instantly forgettable confessors during his time should probably come as no great surprise. But it’s in the characters that the real story lies this time around – the discovery of this new Doctor, and also, for those that have needed it, some real depth of character from the Impossible Girl. Clara has powerhouse scenes with…just about everyone of any importance in the episode, and in particular when with Vastra, with the lead villain and with this new Doctor himself, she shines in a way she’s never been challenged to do before. If Clara and the Eleventh Doctor were a bit smug boyfriend-girlfriend, giggling at the universe, the trauma of this regeneration makes Clara do as much soul-searching as the Doctor does, if not more, and we see, finally, the woman she is becoming, rather than the girl she’s always been. In fact she’s more than a little Sarah-Jane here.

There’s always a moment, towards the end of a post-regenerative story in the New Who era, when the new Doctor shows us really who he’s going to be. Eccleston had hope and a back-up, which went wrong, meaning Rose had to step forward and save both him and the Earth. Tennant had everything from ‘Did you miss me’ through ‘no second chances, I'm that sort of a man’ to ‘six words, just six.’ Smith had ‘to hell with the raggedy…basically…run.’

Capaldi’s final showdown with the lead villain in Deep Breath delivers everything you could wish for in a ‘Dark Doctor’, a grown-up Doctor, a Doctor of whom, while we cheer for him, we're not entirely sure – there’s a dark, quiet, ‘gunslinger in the OK Corral’ prelude, a great, and this time growled, affirmation of his dedication to humanity, a physical battle, a moment of potentially really dark deceit, and a shocking, and as yet unresolved ambiguity. It’s a fantastic sequence, which is less roller-coaster, and more a series of enjoyable punches to the face.

Capaldi blows the immediate past to bits within moments of stepping out of the Tardis. By the end of his first episode, he’s brought to bear some of the best elements of the 70s Doctors, added a pinch of McCoy’s manipulation, and seared his new interpretation onto 21st century Who.

Those who love the 70s Doctors will immediately take this still very New Who incarnation to their hearts. Those for whom it’s not Doctor Who without a bit of snogging are likely to take longer to warm to the Twelfth Doctor. Either way, it’s going to be one hell of a ride. Buckle up – you're not going to want to miss a thing.