First Sight: Frieze, Regent's Park, London

A contemporary show that found its funny bone

This year the Frieze Art Fair, still occupying its giant marquee on the southern edge of Regent's Park, is five years old. Some things feel much the same as before. The fleet of black BMW courtesy cars is still drawn up beside the road for those who, having emptied their wallets indoors, need their egos gently massaged as they purr away in style. The VIP Tent, as usual, is stuffed with peacocks of all sexes.

Other things have changed. There are more exhibitors than ever before – 151 galleries from 28 countries, representing more than 1,000 artists. There is a Frieze Sculpture Park just a couple of minutes' walk away across the park, showing, among other things, a fantastical collaboration between Claes Oldenburg and Coosje van Bruggen of a huge, weirdly tortured and twisted tuba, and several life-size bronze statues by Christian Jankowski. And tonight, at the Round House, Frieze Music will be presenting a performance of Glenn Branca's Symphony No. 13: Hallucination City, scored for 100 electric guitars. Inside the marquee itself, things feel different too. There is more sense of spectacle this year, more colour, more sheer, decorative panache. You have the space to stand back and contemplate. You don't feel as if you are fighting for air inside a sardine can. A lot of the stuff here is big, bright and even brash. But there is, above all else, variety and constant changes of pace from exhibitor to exhibitor. Eclecticism seems to be the rule of the day – hand in hand with a kind of unstuffy, joyous insouciance. One moment you are busy staring at a solemn display of thin and anguished sculptural pieces by Charles Long at the Tanya Bonakdar Gallery's stand; the next, a whole row of Julian Opie pop portraits is smiling at you. As I pass by one of the stands, I read a quotation on a wall by one of the speakers at the fair, the American art critic Dave Hickey: "I would like so see some art that is courageously silly." He could find some here without trying too hard.

There are many serious international collectors for sure, but the place also teems with the general public, who are here to enjoy the fair as an art show. Creative arts student Jackie Johnson Jones tells me: "What I love about it is the sheer range of creative ideas."

There are many moments of lovely, self-deflating humour. I caught a solemn-faced policeman, in full Met kit, sitting cross-legged on the floor, doing yoga. Over at the space occupied by Gavin Brown's Enterprise, a gallery artist called Rob Pruitt is running a flea market, buying and selling like fury.

This year's special commissions include one by the American artist Richard Prince which seems, somehow, to capture the spirit of the fair. A gleaming, yellow Dodge Challenger car, of 1970 vintage, sits, gently turning, on a plinth. Prince tried to assemble it from spare parts, but when that proved impossible, he had it custom-made. Frieze. too. still manages to have that same playful spirit of none-too-pompous versatility.