Just that perfect amount of awesome.
SWTOR provides a unique fully voiced questing / mission system, as well as the alignment system. These features are very common in a majority of the Bioware RPGS, but they have never been introduced into an MMO environment to the extent that swtor does this.
Overall, the uniqueness of the voiced quest/mission, the iconic classes (i.e. Smuggler, Bounty Hunter, and all the Jedi / Sith classes), the personal space ship, lovable companions (Love me some wookies), and the crafting / modification system, make this an MMO worth giving it your all.