V 5.0 was released yesterday to subscribers and included the Knights of the Eternal Throne Expansion
I just started playing it last night and there are lots of fundamental changes to the game itself. Crystals are gone, so when you want to buy mods it via credits. Armor is given through rewards from the look of it or buying sets on the cartel market.
Crafting has also changed, in order to craft to the higher gear you are forced into PVP or operations.
Speaking of crafting you can now craft to level 600 and your character can now level to 70 which is nice because it makes heroics meaningful.
Once you hit 70 you can get access to a personal command console which allows you to quickly access and teleport to heroics and operations and to other things, it also lets you replay chapters of the previous expansion if you wish. this is a great way to shorten travel time.
As for the expansion itself when they talked about choices mattering at the start of Fallen Empire we saw a little bit of that with the deaths of some characters. But the full weights of your decisions hit you in this one
The other thing is that they've improved the graphics and facial software int he game and it looks gorgeous and runs a lot faster.