The Force Unleashed is a linear journey filled with glitches.
The higher difficulty you chose, the more glitches are gonna become common, so its like the game is actually cheating.
Targeting is a disaster, and you will often miss with your force powers. Making you ignore the core features like force grip simply because its awkward to use and too slow in combat. The combos are so long and complex to pull off that you will just ignore them and stick to your first 3 button combo for the rest of the game.
Combos often require use of the force lightning button to infuse your saber with lightning properties, but many times the game wont register your input and will break apart your combo. You will get knocked down often, making the pace of the action stop as it will seem you will be on the ground for centuries before you can jump back up, all while enemies can still damage you.
Levels are short and linear, AI is really stupid as every Storm Trooper just attacks you head on even though you have just slaughtered 30 more right next to him in the blink of an eye.
The story itself also doesn't do it justice, its very basic and can be summarized in a few sentences. If you love Star Wars action then you should consider it if you can find it cheap.