First came the books, then the blockbuster films. Now Harry Potter fans can visit the theme park. The Wizarding World of Harry Potter – almost six years in the making and estimated to have cost around $200m – opened to the public today in Universal's Islands of Adventure complex in Orlando, Florida.

I was there earlier this week to get a sneak preview, along with members of the cast of the first six films: Daniel Radcliffe (Harry Potter), Rupert Grint (Ron Weasley), Tom Felton (Draco Malfoy), Michael Gambon (Dumbledore) and author JK Rowling.

At the entrance to The Wizarding World - a 20-acre area within the Islands of Adventure theme park, rather than its own separate park – visitors are welcomed through a stone arch into Hogsmeade village by a steam-blowing Hogswarts Express train. Before them stretches a scene straight out of the movies: crooked-chimneyed Olde English shops crowd along a winding street, their snow-capped roofs glistening in the Florida sunshine.

There on the right is Zonko's joke shop selling Sneakoscopes and extendable ears; next door is Honeydukes sweet emporium for Bertie Bott's Every Flavour Beans. For fans, the attention to detail from the series will make this feel as close as possible to the "real thing". You won't find a single can of Coca-Cola or a burger – there is only food authentic to Harry's world, such as Cornish Pasties and Scotch Eggs. You can even taste pumpkin juice and Butterbeer in the Three Broomsticks – think butterscotch cream soda.

But the real attraction at WWHP – the one that will appeal to wannabe wizards and blissfully unaware Muggles alike – is the much-hyped Forbidden Journey ride, hidden in the towering spires of Hogwarts Castle, which looks like it has been hacked from granite and left to moulder for 500 years in the Scottish damp.

Once you've made it through the twisting castle corridors to the Room of Requirements, a moving image of Hermione casts a spell on you, and then you're whisked into the darkness on a thrilling CGI ride through scenes from a Harry Potter movie.

Passengers sit on a "magical bench" which, for four minutes, drops, spins and twists in time with the on-screen action. Whomping Willow branches crash out of the dark, then you're flying over the forbidden forest, playing Quidditch with Harry and Ron, and coming face-to-face with hollow-eyed Dementors. Terrifying serpents lurch at you from the mist. Spiders – big ones – spit water at you. And when it's over, the Hogwarts' characters cheer and wave you, like a returning Quidditch champion, back to the Great Hall. You almost feel as if you've wrestled a couple of dragons, in midair, on a broomstick.

JK Rowling who experienced the ride for the first time on Wednesday, when she joined several of the cast for a grand opening ceremony, has been closely consulted throughout. Universal's creative team also worked closely with the Harry Potter film crew, including Stuart Craig, production designer, and Alan Gilmore, supervising arts director, to such an extent that elements that were created for the theme park influenced the later film sets.

At the launch I spoke to Tom Felton, who plays Draco Malfoy. "We shot the footage for the Forbidden Journey about two years ago ... and it's a ride like no other," he explained. "It combines amazing new technology with 3D imagery, with lifesize stuff coming out at you."

"It's so intense. It's like really flying in a real-life Quidditch match," said one visitor after the ride. "I want to go straight back on again."

However, with queuing time predicted to be up to five hours – and with temperatures this week reaching 106F – that may be a challenge, unless you have your own Cloak of Invisibility. While the interactive castle tour is designed to make the queue time a distraction in itself, with talking portraits, a visit to Dumbledore's Office and a Defence against the Dark Arts class with Ron, Harry and Hermione, the queue area snakes for what seems like miles before you even enter the castle. Universal hasn't released predicted attendance figures, but the car park opened at 5.30am today, so fans could be in for a long wait.

There are just two other rides in WWHP – the family friendly Flight of the Hippogriff mini rollercoaster and Dragon Challenge, a high-speed double rollercoaster (with two trains running in opposite directions to create the impression they may crash), that is based on a Triwizard Tournament.

The limited number of rides may be disappointing for some, and at times it feels that half of Hogsmeade is up for sale in true "exit through the gift shop" style. In Ollivander's wand shop the walls are lined floor to ceiling with dusty wand boxes and visitors can have their wand "choose" them, like Harry did in the Philosopher's Stone. A Wandkeeper is on hand to find the right one for you, by asking a series of questions and getting you to try a few out, with mixed but magical results, until a suitable one is selected. It's a fun experience, if also a canny marketing tool for a $25 piece of plastic memorabilia. Next door you can send postcards back home via Owl Post with a Hogsmeade postmark and spend a small fortune in Dervish and Banges on Triwizard costumes, wizard robes, Hogswarts scarves and Golden Snitches. It's clear that Universal is banking on the money-making magic of Harry Potterto rub off on WWHP.

• Day tickets to the Islands of Adventures theme park, including the WWHP area, cost $79 per day for adults, $69 for children on the gate. Open year round. universalorlando.com.

• Virgin Atlantic's seven-night holiday in Orlando, including scheduled flights with Virgin Atlantic from London Gatwick direct to Orlando, accommodation at the 3.5V Best Western Lakeside on a room-only basis with basic car hire included starts from £649 (saving up to £90). Prices are per person based on two adults travelling and sharing a standard room, and include all applicable taxes and fuel surcharges which are subject to change. Prices are based on departures 12 – 20 Nov 2010. virginholidays.co.uk, 0844 557 3859.