This was one of my problems before the expansion release. I don't think there is enough content with the expansion. Masteries and all that stuff are not content. There are 4 zones. If you look at the initial release and compare 4 zones to 30 odd that came with initial release you can see where I am coming from. I bought 3 expansions. I don't mind supporting A/Net because of the value that I have received from the game but it feels like I bought it for that reason and not because I felt the expansion was worthwhile.
I haven't completed any of the new content because I have work commitments but I am almost dreading starting the new stuff because it feels like it will be over in a flash.
A little shallow, unless you enjoyed the 'adventure' style of grinding mastery points then there really isn't much to do. IMO there is little fuel for the fire to go back and do dungeons/fractals and the open world content like events are hit & miss whether you can get a decent group. I'm feeling a little strapped for something to do whenever I log in.
Will see how much the raiding environment changes this.
if you wait for the price drop, you wont be missing out too much