The Met Gala is the Oscars with the few remaining unphotogenic parts Photoshopped out. No old people, no crying (after three hours in makeup, are you insane?) and pretty much no women who weigh more than eight-and-a-half stone, although exceptions are occasionally made if one is carrying a baby with A-list pedigree. There is no need for an awards ceremony, because this event is won or lost in front of the wall of paparazzi, who gather one night each May on the steps of the Metropolitan Museum as the New York fashion industry compete to impress their host, Anna Wintour.

The dress code is guided by the theme of the Costume Institute exhibition. Last year was punk, which meant safety pins and tartan and ripped everything, and maybe Wintour didn't love it, because let's just say this year's exhibition is more traditional – a retrospective of the Anglo-American couturier Charles James, creator of epic pastel ballgowns for society swans – and the dress code for the opening night was "White Tie and Decorations". Can the power of Wintour turn the tide of popular culture and enforce dress code decorum on an industry hooked on social media and personal branding? Who were the night's winners and losers? It's time to rip open the envelope and find out …

Best dressed

Cara Delevingne

It's a party. Dress codes are not school rules; they should be followed in spirit, and with spirit. That's what Cara, dressed by Stella McCartney, has done brilliantly here. She is wearing trousers and a crop top instead of a ballgown, but she looks elegant and she looks glamorous. The trousers are perfectly tailored (stretch would look wrong) in a fabric that is suitably upscale and grand; her hair and jewellery choices are straighter and more sophisticated than usual (danglers instead of lobe cuffs, waves instead of plaits). Bravo.

Beyoncé

Bey currently stars on the cover of Time magazine, heading the annual rollcall of Most Influential People. Much attention has focused on her skimpy outfit. In a nutshell, ICYMI, yay for a black woman being most influential, but does she have to be most influential in her pants? This outfit – glamorous, formal, mysterious and covered-up with sleeves, a long skirt and a veil – is a Queen Bey smackdown to all that. The veil and bun are chic and grown-up, but the cleavage and split skirt make it feel sexier and younger. The tiny silver spikes worked into the embroidery of the dress, and the matt damson lipstick, are signature modern-goth touches from Riccardo Tisci of Givenchy, creator of this dress.

Emma Stone

Charles James would have loved this look. In the most famous image of his work – a Cecil Beaton photograph of seven women in his gowns – one of the dresses is ice blue spliced with lemon, while another is pistachio draped over gold. The skirt of this Thakoon piece is classically shaped, but the sporty top half gives it an Alexander Wang-esque relevance to modern New York, and the sliver of tummy puts Stone in a girl gang with Cara Delevingne and Rihanna, which is never a bad place to be.

Alexa Chung

This is really clever and really sweet. Alexa has always been annoyingly good at making old-school femininity look modern and interesting. Remember when she used to wear little Peter Pan collars, and yet somehow just by adding a cross-body handbag and a slightly raised eyebrow you got that she was in on the joke? This Nina Ricci dress is the white tie equivalent of that. The fabric looks as if it walked straight out of Charles James' atelier – you don't see a lot of ice blue silk taffeta on the streets these days, although I imagine someone in Topshop head office is on the phone buying up a few bolts right now, so that may change.

Claire Danes

Here's how you wear a sweetheart neckline with pink and make it look sharp and chic. Reese Witherspoon, are you watching? The dramatic contrast in colour and texture makes an age-old ballgown template look up-to-date and interesting, and the styling is perfect: whopper earrings peeping through the perfect tendrils on your too-cool-for-school updo, no necklace.

Worst dressed

Lupita Nyong'o

Yeah, we're going there. Sorry, world, but, you know what? Lupita's a grown woman, a superb talent, an Oscar winner; it seems unnecessary to patronise her by pretending this dress works when, let's face it, it really doesn't. Charles James was about line and simplicity and elegance, and the women who rocked the red carpet got that. This dress is teetering from fancy party to fancy dress, the flapper references don't fit either with the James or the modern era, and there is altogether Too Much Going On. It's a Prada look, not a Lupita look. If you ask me, Miuccia's people are having too much input, and Lupita's people need to exercise a little pushback.

Rita Ora

I am, obviously, 100% in favour of women wearing whatever they feel good in and not being censored in their choices. And yet, now and again an outfit comes along that sorely tests my ability not to get really judgey. For instance, if a young woman invited by ANNA WINTOUR to the most elegant, refined, gorgeous evening in the METROPOLITAN MUSEUM OF ART chooses to wear, say, shiny gold lace-up peekaboo thigh-high boots, and a skirt split to the waist so that you can see her actual knickers, and more net and sequins than a Disney Store party dress, I can't help feeling a little bit disappointed. Shoot me.

Reese Witherspoon

Babe, you've basically been wearing this dress since Legally Blonde. It feels like a metaphor for your career, and not in a good way. Also, Stella McCartney is making you dresses, so it's not like you don't have the option of kicking things on just a teeny bit in the frock department. Pink lipstick with a pink dress and mega-rollered hair: it's a bit kitsch, frankly. And it probably plays well in the heartland but the Met Ball is all about impressing the cool kids.

Kate Upton

Wow. I mean, thanks for the lolz, Kate, but what were you thinking here? This is comedy-bad. "I want to look kind of like old-school? With one of those big skirts. And a corset. And we gotta put major frills on it to make it super cute. And like, flowers in my hair! Yay! But still, y'know, super sexy, so maybe it would be cool if it looked like I wasn't wearing any knickers? OMG guys this is going to be so awesome!!" No, Kate. No, it isn't.

Anne Hathaway

Am I reading this wrong? I just find this joyless. Bloodless and pointless and joyless. If you're going to dress up for a party, where's the va va voom? I mean, you're there on the arm of Francisco Costa of Calvin Klein, who's designed the dress, and yet it looks as if you got changed in the ladies and forgot to do anything about the traffic warden hairstyle. Is that mean?