Alright I just finished the game.
I´d like to start off by saying that the game definitely is worth the price. Drakan said already, though: The Force Unleashed II shares a lot of similarities to the first one. Many are much more improved, mainly combat. So, if you like the first, I'd say you should get this one, too. There's not very much to say, but I'll keep it short and good, and will avoid storyline spoilers.
Cinematic [+]: very, very well done. It's somehow much more 'realistic' than before, and also much more 'immersive'. I also love how the cinematic scenes are not ignoring which lightsaber colour you chose. In The Force Unleashed, it did. I'm trying not to spoil anything, so I won't talk about the scenes near the end. It was quite emotional if you ask me!
Combat [+]: much more improved, as aforementioned. While you do keep most powers from The Force Unleashed, The Force Unleashed II has some new cool things too, such as the ability to mind trick, and use "fury", which can be seen in the demo as well. Enemies are not much more harder than The Force Unleashed. In-fact, the difficulties in this one seem to be much more easier compared to the first (easy compared to padawan in the first, etcetera).
Playtime [-]: the amount of time needed to finish the game isn't really that much impressive, to be honest -- a good 6-7 hours. I expected it to be much longer than it was. The campaign has 9 levels in total, so I could imagine.
Rating on a scale of 1 to 10
Originality: 8.5/10
Story: 9.5/10
Cinematic: 9.5/10
Playtime: 5.5/10
Overall: 8.25/10