Testosterone and thunder collide with the release of Thor, the first official blockbuster of the summer movie season and a precursor to next year's The Avengers. The movie, curiously helmed by Shakespearean director Kenneth Branagh, is an entertaining start to the season but unfortunately not the knock-your-socks action extravaganza you may be expecting.

Thor, which stars Chris Hemsworth as the title character and Natalie Portman as his mortal concubine Jane Foster, is the riskiest comic book adaptation to date. Unlike the other franchises that have taken off in recent years - from Spider-Man and X-Men to Batman and Iron Man - Thor is the most fantastical of them all, with much of the movie set in the Godlike world of Asgard and relying very little on the physics of the real world.

The movie is first and foremost an origins story and shifts between modern day Earth, where Thor meets Jane and attempts to retrieve his hammer - and his powers - from S.H.I.E.L.D., and Asgard, where adopted brother Loki (Tom Hiddleston) attempts to seize power from their aging father King Odin (Anthony Hopkins).

While necessary, Thor struggles with the typical elements of origin tales. Specifically, it must balance character development with the action everyone expects. Unfortunately, while Branagh strikes a decent balance, Thor isn't as epic or thrilling as it could have been.

Thor doesn't have much action, especially not as much as you'd expect from the god of thunder. Thor spends much of the movie without his powers. This doesn't keep him from kicking some human ass, but once he does regain his full might, he quickly dispenses with his earthbound foe and then the picture moves onto its quick climax.

Thor seems incomplete as a result, but then again that's the point. It is, after all, a setup for The Avengers, nothing more.

While the lack of a truly awesome action sequence was the biggest issue, the movie also struggles with a paradox presented by its two key settings. The scenes set on earth are extremely entertaining, funny and enjoyable, but they also are just filler. Every important scene takes place in Asgard, but ironically they are less engaging.

Unfortunately, the relationship between Thor and Jane also seems forced. When Thor promises he'll return to Jane, it comes as a surprise that the two had formed such a bomb. It feels as though several scenes developing their relationship were left on the cutting room floor.

Nevertheless, Thor is still a worthwhile movie. Relatively well written given its source material, Thor sets the groundwork for a strong franchise. The movie was from the outset a challenge to pull off, and Thor works more often than not. Chris Hemsworth is excellent, bringing charisma, energy and humor to a character that could easily have none of those things.

Though it lacks a truly memorable action scene, there is enough excitement and intrigue to keep things entertaining. Thor isn't perfect, but it is a fun start to summer.

Review by Erik Samdahl unless otherwise indicated.