Peter Capaldi's run at the 12th Doctor has begun. So how'd it go? Here's how we grade "Deep Breath."

Spoilers ahead, sweetie.

The new Doctor: A

Put simply, Peter Capaldi killed it. Every bit as brilliant at owning the role as fans expected, Capaldi was by far the highlight of every scene he was in. And God bless showrunner Steven Moffat for giving him so many great lines to chew up and spit out with that glorious Scottish accent.

This regeneration was unlike any other we've seen in a long time, largely because it was the start of a whole new cycle of regenerations. This caused it to affect his system in a more physically jarring, violent way. It also slowed his transition from Matt Smith-esque fast-talking madness to 12 finding himself and his own way of doing things. Watching that slow burn was incredible, and Capaldi did it masterfully.

This is a very different Doctor to the last one, but that bit was hammered home a little too much. He's older in appearance, we get it. Did it really need that much attention drawn to it? A physical difference of 25 years or so shouldn't be that big a deal when we're talking about a 2,000-year-old being.

The Doctor/companion relationship: B-

Obviously, it's not quite there yet, but they're working on it. There were plenty of great moments: Clara's early exasperation with the Doctor's faulty memory and that touching final moment after her phone call spring to mind. But their best chemistry was during the scene where they rendezvous in the restaurant. They played off each other beautifully, mixing humor with suspense, and showing just how well these two still know each other.

Murray Gold's theme for the 12th Doctor: A-

Composer Murray Gold stumbled onto something magical when he devised the instantly memorable theme for Smith's 11th Doctor. It perfectly conveyed the whimsical but wildly exciting nature of the character, and it was crazy hummable. Gold's theme for Capaldi — which we only heard a few samples of — is just as exciting, but not quite as memorable. It should serve 12 well, but 11's theme was so perfect it'll probably never be topped.

The new title sequence: C+

The new visuals are terrific. After 50 years of tumbling through the time vortex, it's definitely time for something new and different. The steampunk gears and spiral clockwork are an inspired choice, simultaneously feeling both modern and retro.

But the music darn near ruins the whole thing. It starts out well enough with some thumping bass, but then those weird, high-pitched strings kick in. It's an unsettling sound, which is maybe what Gold was going for, but he went way too far with it. It sounds like a dying cat trying to sing the classic "Doctor Who" theme. Ugh.

"Deep Breath": B+

As always with Steven Moffat, it was a very smart game of connect-the-dots, filled with twists and terrific dialogue. Where it suffered was in its pacing. A slower pace is not a bad thing; at times, the madcap fairy tale that was Matt Smith's run could be a little hard to follow. But there were a few disposable scenes that did nothing to advance the plot or explore the characters, such as Strax's medical examination of Clara. It was cute, but totally unnecessary.

The most surprising aspect of the episode was that just as much time was spent on defining Clara as was spent defining the new Doctor. And it was greatly needed. As a companion, Clara has always been a little two-dimensional; the mystery of who and what she was overshadowed any chance she had at characterization during her first season. (She was more interesting in her earlier appearances — "Asylum of the Daleks" and "The Snowmen.") We now have a better handle on who she is, and this was the episode where she finally stepped out of Amy's shadow.

Vastra, Jenny and Strax were reliable when the Doctor (and we) needed them. These three actors have settled so comfortably into their roles, it's always a treat when they guest star.

The only part of "Deep Breath" that was a little hard to swallow was the notion of Clara being so thrown by a new regeneration of the Doctor. This is the Impossible Girl we're talking about, the girl who lived through all of the Doctor's previous personas. If any companion has ever been prepared for the realities of Time Lord regeneration, it should be Clara. But okay. As with all things "Who," you'll have more fun if you just sit back and go along for the ride.

The show's production values have never been higher, so bravo to the entire crew. The effects have moved up a notch or two, and the use of color grading, dynamic movement of the camera and varied real-world location shots gave the episode a grand, cinematic scope.

Overall, it was pretty strong.

Prospects for Season 8: A-

It's off to a promising start. If Capaldi and Jenna Coleman can nail down their chemistry, and Capaldi is allowed to develop more warmth for his Doctor while not losing his harsher, more alien edge, then this should be a fun season.

This season's big mystery seems to center around the new character we met at the end, Missy, played by Michelle Gomez. It looks to be a juicy one, as fans are already speculating on her identity and connection to the Doctor. But there's really only one person she could be, and if you're paying close attention, you already know who that is.

So I'm calling it now, on the record, though I'm hardly the only one to put forth this theory: Missy is a female regeneration of the Doctor's arch-nemesis, the Master. Re-watch that final scene and study her expressions, her personality, her off-kilter insanity. She's obsessed with the Doctor, she knows him very well, and she's been meddling in his affairs for a while now. And reinventing this character as a woman is exactly the kind of thing Steven Moffat would do. Even her name is a hint.

Missy = Master. You just watch.

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