A Great Beginning for the Marvel Cinematic Universe

Rating: 9/10 (8 January 2015)

This film is not the first movie to feature characters from Marvel Comics. The 2000's saw the "X-Men" franchise, a "Hulk" movie, two "Fantastic Four" movies, and the Toby Maguire "Spider-Man" trilogy. However, all of those movies were films that Marvel outsourced to various companies--notably Fox and Sony. "Iron Man" is the first film to be made in house by Marvel Studios, and as such it's the first film in the Marvel Cinematic Universe, i.e. the first film that will come to interact with characters from other films that are not direct sequels.
For this reason, "Iron Man" is worth watching if you happen to be a fan of any of the other MCU movies, especially "The Avengers" series. "Iron Man" begins the process of building continuity across different Marvel films, and for the true nerds amongst us there are many tidbits of information in this movie that are beneficial to understanding the rest of the MCU films.
Still, the main reason to watch this movie is not its place in the MCU, but its value as a standalone film. Marvel Studios set out to prove themselves with this movie, and they delivered a hit. The film is a solid two hours of thrills that features a robust and engaging storyline and fantastic acting. Robert Downey, Jr. defines the role of Tony Stark, and Gwyneth Paltrow, Terrence Howard, and Jeff Bridges all turn out dynamic performances. Bridges especially shines as Obadiah Stain, and contributes much to the movie.
That said, I give this film nine out of ten stars. It's one of the best in the comics movie genre, and I only stop myself from giving it a ten because I try to reserve that score for movies I see as not only great, but perfect. "Iron Man" comes mighty close to that, and I'm sure you'll agree that it deserves high marks.
Oh, and don't forget to watch the post-credits scene, which foreshadows the rest of the MCU!