At the end of Halloween 2 2009, Laurie kills Michael with his own knife, walks out wearing his torn mask, and then appears in a psychiatric ward, smiling as her mother's ghost approaches with the white horse. Before that, Michael kills Loomis in the shack, and Sheriff Brackett shoots Michael through a window, so that he falls onto farm equipment. Laurie finishes him.
What does the last scene mean? In my opinion, it shows that Laurie has taken on the thing that haunted her. Seeing the ghost of Deborah Myers arrive with the white horse suggests the cycle has passed to her, and the torn mask she carries out of the shack is the visual hinge for that idea. It could be argued that her smile reads as peace and as breakdown at once, and the film does not choose between them.
How does that compare with the rest of the series? In Halloween II (1981), directed by Rick Rosenthal, Laurie is sedated at Haddonfield Memorial Hospital and Michael comes to her, so she is a patient being hunted. Here she is a patient at the end by a different route: she has won the fight and still ends up in a ward. Halloween: Resurrection (2002) also opens with Laurie in a psychiatric facility, but that film belongs to a different timeline, and the two should not be read as connected.
The film also leans on its sibling story. The 2007 film shows ten year old Michael sparing his baby sister, and this sequel pays that off when Laurie learns that she is that sister, born Angel Myers. As such, the ending is less about whether Michael is dead and more about what the family inheritance does to Laurie. Loomis, who spent his career insisting that Michael could be understood, dies in the shack without being heard, which I find the most bitter beat in the film.
There is also an alternate ending that Zombie filmed. In it, police fire on Laurie, which leaves her mentally broken, and the film does not set up a clear continuation in either version. Sourcing note: Zombie used John Carpenter's original theme only in the final scene, according to Wikipedia read alongside Box Office Mojo, so the one piece of the 1978 sound arrives exactly when Laurie takes the mask.
Is Halloween 2 2009 worth watching? If you want a bleak, character driven take on Laurie and Loomis, it is the version to try. If you want the stalking suspense of the original, halloween 1978 is the better fit.