Yes, yes, yes, yes. This movie rocks. In fact, I can't think of a single reason not to buy it.
Let's start with the cast. The two juggernauts Ian McKellen and Patrick Stewart are in the centre of this epos, going head to head against each other - one militant using force to establish a new world order where mutants are at the top, the other wishing to build bridges between mutants and humans for a better understanding; justice and peace for all. Then there's Halle Berry (hot as usual) as a quite convincing Storm, Famke Janssen as the graceful Jane Grey, Anna Paquin as the fugitive Rogue and Hugh Jackman as the wild and mysterious Wolverine. There is not - in my opinion - a single cast member who does not play his/her part well, and they are all well-suited for their respective roles.
The plot is what makes this film stand out. The focus is on the difference in philosophy between the two old friends Xavier and Magneto, the appearance of a new powerful mutant named Rogue and her encounter with the loner Wolverine. The film is an introduction to the story of the X-men, and is very well suited as the beginning of a trilogy. Wolverine is an important character: basically, he's a mystery. He doesn't remember much about his past, and throughout this film (and indeed in the next) he quests to learn more about himself while at the same time opening the door to his heart in one rare instance for the vulnerable Rogue, who is placed in the middle of the battle between two old friends who have different views on the relationship between humans and mutants.
The film will leave you with a desire for more. Trust me when I say you don't really need it. This film yields a preliminary result of a continuing battle between the two great old men, and that's the way it should be. You can always continue the story yourself, in your own imagination.