There is no doubt that the Avengers is the best comic book based movie of all time. I will take that further and say it is one of the best movies in general. It had the biggest ever opening weekend in the US, a whopping $207 million, and did it by beating the previous holder of that title, 'Harry Potter and the Deathly Hallows: Part 2' by almost $40 million.

The $1 billion mark is in sight.

But why is this movie the most successful films ever?

This movie had a long time to setup. After years of laying the ground work with the individual character films, the Avengers assembled.

First Marvel's released Iron Man, with a wise-cracking Robert Downey Jr. as its lead in 2008. A scene following the film's credits teased an Avengers film in the future. This was a great kick start for the franchise and Downey's Tony Stark is dead on. Hulk, Captain America and Thor, each had their own movies as well, which set up each of the lead characters and familiarized the audience with the Marvel universe.

With Avengers, Marvel took a gamble by entrusting their flagship property to a director with only one big screen credit.

While critically lauded, geek god Joss Whedon's debut 'Serenity' was still a flop. However his work on cult TV shows 'Buffy the Vampire Slayer' and 'Firefly' proved that he was adept at writing and directing ensemble pieces. He also had experience with Marvel, having written a string of X-Men comics in 2004.

Whedon proved to be the perfect man for the job, skilfully dividing up screen-time between the heroes, the supporting characters and the villain, without ever detracting from the overall story. And he did it all with a keen sense of humour, making the film funnier than most mainstream comedies.

His hiring followed the Marvel pattern of leftfield directors: 'Elf' helmer John Favreau took care of 'Iron Man' and its sequel while Kenneth Branagh 'Thor'. All three ended up doing fine jobs.

A great cast
Before Robert Downey Jr. became 'Iron Man' in 2008, he was best known for stints in rehab. Sounds like a Tony Stark in the making to me. That film was made for him, and set the blueprint for Marvel thinking outside the box when it came to their leading men and women.

Chris Evans and Chris Hemsworth both nailed their parts as the American golden boy Steve Rogers and Norse god Thor, neither of which were what were expected. Then there's Tom Hiddlestone and Mark Ruffalo, two indie darlings who undoubtedly steal the show as Loki and The Hulk respectively.

With the exception of Downey, the most recognizable stars involved weren't even super-powered,  Samuel L. Jackson and Scarlett Johansson.

Ask anyone what their favorite moment from The Avengers is, and the chances are they will mention something involving The Hulk. My favorite, and many others as well, has to be his only line of dialect. "Pewny God"

Despite two films that failed to do him justice, and with a third actor now taking on the role, everyone still loves the big green monster.

What helped this time around is that Whedon moved away from the angst-ridden, tortured versions of the character played by Eric Bana and Ed Norton. He retained the hint of tragedy that the character needs but made him entertaining and FUNNY as well.

The most creatively bankrupt way of evolving a series is to "go darker".

As the years went by 'Harry Potter' got bleaker while 'Spider-Man' went from light romp to emo-inspired rubbish. Only Christopher Nolan's Batman trilogy got away with it because it was dark in the first place (and really really good).

The Avengers have bucked this trend. Across the five build-up films and 'Avengers' promotion, the sense of fun has never diminished. They remain bright, colourful films that are entirely self-aware and proud of their comic book heritage.

Inherently ridiculous and damn proud, the Avengers chime into a deep-set feeling of nostalgia that everyone has. A nostalgia for movie stars that quipped more than they frowned and for larger than life characters who fight for good and do it with a nod and wink.

The Los Angeles Times called 'Avenger's Assemble' "smartly thought out and executed with verve and precision", while the Hollywood Reporter said it was "engineered to charm the geek core and non-fans alike".

And that's the point. Films based on comic books have an inbuilt core audience that will usually watch them no matter what. But for a superhero franchise to appeal outside the fanboy set — and make loads of money - they need positive word of mouth. Which typically means good reviews.

It's no coincidence that the two most successful superhero films ever are also the most critically lavished. Right now 2008's 'The Dark Knight' has a 94% rating on Rotten Tomatoes, and 'Avengers' has 93%.