'Avengers' News Assemble: Reviews, Mondo Posters, Late Night Shows and Box Office (Photos)

The Marvel superhero team-up is drawing major buzz and making news as it begins opening around the world.

Marvel's Avengers was always a risky proposition; any film this big, with this many big name stars and superheroes, could either be a massive hit or an unwieldy, studio-dictated mess. A week ahead of its United States release, there seems to be no question that it will be a cultural phenomenon and financial goldmine.

Critically, the film has garnered rave reviews. THR's chief film critic Todd McCarthy writes that, "Director Joss Whedon pulls off a stunning feat in bringing balance to this superhuman circus, engineered to charm the geek core and nonfans alike," and his sentiment is shared by nearly every critic to have published a review thus far. 

Currently, the movie has a 95 percent fresh rating on the reviews site Rotten Tomatoes, with 38 positive reviews to just two negative evaluations. Christy Lemire of the AP chimes in, "The dialogue sparkles as brightly as the special effects; these people may be wearing ridiculous costumes but they're well fleshed-out underneath. And so in every regard, this movie truly fulfills its hype."

And hyped it is, from mainstream moviegoers to comic fans to hardcore fans of Whedon himself, who are as active as any group.

PHOTOS: Avengers Assemble in Official Film Stills

Already, the film is breaking box office records. It had the biggest opening day in New Zealand history, opened with the second highest gross in Australian record books, and took in $3 million France, earning $12.5 million internationally before it even fully opens in foreign markets. Expect big numbers from all those other markets; the film has been holding massive premieres in countries such as England, Russia, Germany and China.

With a massive cast -- Robert Downey, Jr. (Iron Man), Chris Evans (Captain America), Chris Hemsworth (Thor), Scarlett Johansson (Black Widow), Mark Ruffalo (Hulk), Jeremy Renner (Hawkeye), Samuel L. Jackson (Nick Fury), Tom Hiddleston (Loki), Cobie Smulders (Maria Hill) and Clark Gregg (Agent Coulson) -- expect all headlines and late night shows to be dominated by Avengers stars.

Already, Smulders has appeared on Letterman, while Hemsworth is due on the Late Show on Friday. The Tonight Show will welcome Johansson next Wednesday and Downey Jr. will visit Leno the next night (during which time Johansson will be on Jimmy Kimmel Live!). Evans will appear on Late Night with Jimmy Fallon on Monday, while Ruffalo joins that show on Tuesday, followed by Live! with Kelly on Wednesday.

Then there is the matter of hardcore fan reaction -- and merchandising. The reaction from comic fans and film blogs has been unanimously positive.

Ain't It Cool News' Harry Knowles tweeted on Wednesday, "AVENGERS is easily the best MARVEL film, and it isn't even close. In fact it has its own constellation of f--king awesome all it's own!" while Film School Rejects' Neil Miller tweeted, "You guys remember when you were a little kid and thing were awesome and fun? That's what it's like to watch THE AVENGERS!"

To those that scoff at the film for being a mere superhero tale, Hiddleston has a rebuttal. The star wrote a passionate piece in the London Guardian newspaper last week defending superhero films as gorgeous and important tales of humanity that tie the world together.

Also on Wednesday, The Alamo Drafthouse/Mondo and Marvel unveiled new, artistic and limited edition character posters (in addition to the three they already released), which are already drawing buzz. Captain America and Hulk are below.