THU2 is a short game. I finished it yesterday on medium difficulty, using a keyboard and mouse interface, no controller. It basically took me 2 days. Tuesday a few hours (4?), Wednesday a few hours (3?), and Thursday a few hours (3?). I have not collected all the holocrons or unlocked all the extras yet. Apparently you need to do the challenges to unlock everything else. I finished the game with the light side then went back and reloaded and made the dark side decision.
Overall, it was a fun game, but very short. I'm happy I didn't have to shell out 60 something dollars for a game that I completed in less than 12 hours. Only the Wii version comes with a multiplayer mode, so you get better value there. The other console versions are only single player.
The challenges I mentioned before for unlocking other extras, those can be done online or offline. Basically, you just do some game tasks, like completing lightsaber combos against a timer, or kill as many troopers as possible against a timer, etc etc. Through the course of the game you unlock all the databank and concept art, some of the costumes, and some of the challenges. If you collect all the holocrons you unlock a lot of the saber crystals. I think I missed a few so you might actually be able to get all the crystals if you play through.
Is there a playguide available?
Yes.
Do you need it?
No. Not once did I need to consult some type of guide or notes. Very linear play. And if you ever find yourself wondering, what direction do I go next? There is a handy force power that makes a glowing ball shoot in the direction you need to go.
Are any enemies really hard to kill?
For the most part if it's a new or special enemy the game tells you how to kill it by introducing some new mechanic such as using force grab or lightning or mind control. Really hard to kill is a relative term. The game tells you how to kill most of the enemies so that eliminates the figuring it out part, all it really leaves you with is skill/difficulty level. Boss fights can start to feel monotonous because some seem to drag on.
Can you upgrade your powers?
Yes, there are a total of 3 power levels per force power, they cost points to upgrade. You get points by killing things.
Can you upgrade your lightsabers?
Yes, you use crystals. Unlike KOTOR you only get to put one upgrade cyrstal in the saber at a time. You get two sabers so you can mix or match the crystals. The color of the sabers is determined by the crystal used. Each crystal has a different effect..
Anything else?
I cannot think of anything at the moment but feel free to ask me.