X-Men: The Last Stand begins with a so called "cure" being created for the mutants, a cure that transforms them back into a regular human being. Magneto (Ian McKellen) doesn't take lightly to this news and bands together an army of mutants who are determined to kill all those responsible for the cure. The X-Men must now get over their mourning and previous issues with each other to band together for one last fight against this rebellion.
X2 set this up to be something big that ultimately ended disappointingly. If you have not seen X2 I warn you that I will be talking spoilers in this paragraph. The second film in the X-Men series concludes with a war raging up and the recently deceased Jean (Famke Jannsen) returning as Phoenix. When Bryan Singer departed this project to film Superman Returns, practically everything that was in the original script was torn to shreds and a new film was developed. I do not hate this movie, but the final product does come as a disappointment over the previous two instalments.
With all the flaws that this film has there's still plenty of fun to be had. I will get nitpicky with this movie very shortly, but with those soon to be announced flaws aside this movie is a lot of fun. Wolverine (Hugh Jackman) returns to his badass, occasionally hilarious ways and the action throughout the film is a blast, literally in some cases.
The few action sequences that are present in the film are mostly impressive. The X-Men films have never been about exploding action in our faces for the entire runtime of the movie, but the action is never invisible either. It's always been a series with good character development. In X-Men The Last Stand all the character development is thrown out of the window for an action packed and unsatisfying conclusion. While there are many problems with the ending, the action that takes place is a lot of fun. Seeing a bunch of mutants fight to the death on an isolated island can rarely disappoint. Well for the most part anyway.
Plenty of characters in the film are completely wasted. WARNING I WILL TALK MAJOR SPOILERS IN THIS PARAGRAPH! A few characters that are featured in the superior X2 are jus ignored and not even mentioned in this film such as Nightcrawler, a fan favourite. Not to mention that plenty of other characters are tossed away like they're nothing in the first act such as Cyclops who dies practically straight away and Mystique who is cured soon after. Towards the end of the movie they also cure just about every bad mutant as well as kill off many of the good ones. It's just ridiculous to see them pointlessly kill or cure several of the key characters.
To sum up, X-Men: The Last Stand is disappointing after the previous films and has many problems throughout, but there's still lots of fun to be had with it such as impressive action and good old Wolverine badass-ness. Yeah that's about it.