And it raises your lvl max to 55, so if u get it and finish your main story quest before u start, you can be over leveled/ max lvl before you even start RotH. (Which to me was a good thing)
^^^ This, so I'd wait until you're level 49 to buy it.
And if you're not done with your class quest before buying it, try to avoid clicking on your ship's holoterminal, even though it has the quest marker over it, because, yeah, spoilers. :P