I've gotten it last night, and I'm only about 4 hours in so far. (I did the sensible thing and peeled myself away from the TV at 1:00AM. One more hour here, and I can finally go home...)
It's hard to make any big statements at this point, but some improvements from the first one are apparent: The conversations are deeper and have more different and relevant dialogue choices, various skills and Abilities (not just Persuade) have impact on dialogue and the solutions to various puzzles, and more effort is being made to give some of the easily marginalized characters (like droids - T3, which makes a comeback in this game, foremost comes to mind) more personality.
Another change - haven't decided whether I like it or nto - is that you can craft items now, or disassemble them for parts - for example, you can make a power cell to use in an upgradeable vibroblade, or make a medkit, or a sonic grenade, or a new armor underlay, etc. - exactly what you can make depends on what skills your main character has. The upgrade process for weapons, armor and lightsabers that existed in the first game is still intact, and I'm not 100% sure whether this new crafting system will enhance it, or detract from it by making upgrades too easy to make yourself - hopefully, the best stuff you'll still have to find or be very high level to make.
Weapon Finesse has made its way into the game, which is something I'm sure most d20 fans will appreciate.
More as I get more playtime...