Just finished this game, and I have to say that it far exceeded my expectations.
The Demo presented two levels: one that was heavy on targets--er, people with guns, and one that was heavy with Dark Force users. The run-n-gun level left me pretty cold, but the Force heavy level gave me quite a thrill. If the game had been balanced like the demo, I'd not have enjoyed it so much.
It turns out that the game mixes up the action pretty well between Force use and run-n-gun, but leans toward the Force. Indeed, I can't talk terribly intelligently about the weapons in the game, becuase I barely ever used them. After all, why would a Jedi need anything other than his trusty saber(s)?

The game is structured into three main 'acts'. Each act presents five missions that you can play in any order, as well as at least a couple of missions 'forced' missions. The forced missions introduce or close out an act, and represent major plot points, so have in-engine cutscenes and the like.
The missions are mostly go-here-do-that-defend-yourself sorts, but there are some pretty interesting off the wall ones too. You'll find yourself runng from a Rancor, racing speeder bikes, escaping a prison, and squaring off with notorious bounty hunters.
Before each of the player-selectable missions, you can allocate a single point to one of your non-core force powers (stuff like Force Sense and Mind Trick). Core force powers (like Force Jump or Saber Defense) only increase after the 'forced' missions. There are exactly enough missions, if you take them all, to get three levels in each of five (out of eight) force powers.
I went the Light-side route and got Healing, Protection, Mind Trick, and Absorb maxed out. With my spare three points, I went for the only Dark power that is worth a damn (in my opinion): Force Grip. There's nothing like choking the living crap out of a Dark Force user while you throw your lightsaber through his guts.
Some of your powers, like Force Speed and Force Jump can be used to pull of some nifty moves, like running along a wall sideways, or running straight up a wall and backflipping off. Both are excellent in saber duels.
Speaking of sabers, you start out with your own lightsaber, which is, in my opinion, one of the smartest things they did in this game. Every other Jedi Knight game has you start without it. Through the course of the game, you'll be able to select from two saber styles (fast or strong, you already have the default medium style). Late in the game, you'll be able to elect to use two sabers, or a Darth-Maul style double-saber. Double saber and dual saber modes take over your medium saber style slot (becoming the default). I went with two saber style and was immensely pleased. Because the game goes into slow-motion when you slay a Dark Force user, you get treated to some flashy kills. With two sabers, you can get into a saber-lock with your opponent. While you press him with one you'll sometimes release the other to fly around behind your target and cut him down. Its lovely.
You'll face a huge number of Dark Force users in this game--more than there were in Jedi Outcast, certainly. The designers did a far better job using the Dark Force users in Jedi Academy than they did in Jedi Outcast too. In Academy, they will work in teams, sometimes both attacking with sabers, and sometimes one standing back and using Force powers (and sometimes guns too!).
You'll also meet more stormtroopers than ever before. Everything from heavily armed tank-like armored troopers, to flying troopers, dark troopers, and the various sorts of vanilla troopers will come after you.
The maps for the various levels vary from medium to absolutely huge. One level took me almost six hours to work my way through, it was so large. Others, you'll finish in no more than an hour or two. The textures and the model use in the levels are good, though sometimes its hard to tell if something is an object you can interact with or if it is just decoration.
The only bad point about this game (and there is only one) is that it lacks stealth play. You can't play this game as Shinobi, Jedi Ninja. It just won't let you. Stormtroopers, Dark Force users, Noghri (did I mention them? Its got Noghri

) and mercenaries will notice you instantly when you walk into an area, even if they can't really see you. Its gotta be those Jedi boots. They're loud.
I can't recommend Jedi Academy enough. It easily outdoes its predecessor in every way possible. The game is engaging and entertaining and most of all, addictive. I played obsessively through to the end over the course of this last week, which is something I seldom do (and never with first person shooters). Hell, I even played without cheats!
Other things to note: you create your character. He's not premade. You can play a male or female Human, female Zabrak (think Darth Maul) or Twi'lek (tentacle head), a male Kel Dor (crab faced guy), or a male Rodian. I went with the Kel Dor. They look cool. You get to pick from several different heads, torsos and legs, as well as set a primary color, with various effects (on a Kel Dor, the color changes the clothes, but on a Twi'lek, it changes the skin color).
You also get to pick your lightsaber. There's several different hilts and different colors of blades. The hilts have various names and some blades are more thicker and thinner than others. I used the the tapered hilt (Defender, I think) with a yellow blade and a Firebrand (dark, simple hilt) with a lavender blade. None of these make any difference whatsoever, but they certainly look cool.
