If you're in to all things X (or, cheesily, if X marks the spot for you), you need this cut of the film.
As well as the titular Rogue sequence that was not in the theatrical release, this version has many slightly different scenes with alternative dialogue.
You don't even have to choose: this edition contains the theatrical release as well as the new cut.
10/10 for me; one of the best X-Men films by far, to date.