Ugh, I'm not supposed to give intricate details or anything, but I think I'm at liberty to say that the fighting is good, but the user interface is more appropriate to the typical MMO and that nothing of KotOR except the core mechanics remains unaltered.
The story is engaging from what I've played, and the dialogue is great, but the conversation is very heavily influenced by mass effect, almost to the point where it no longer resembles KotOR; the harrowing moral choices are back (I can recall one that kept me thinking for ten minutes:P), and getting into the role comes as naturally as it did in KotOR, or ME for that matter. Also some polish and immersion is lost due to what I could only call "Dumbing down" for the typical MMO market. No offence typical MMO players.
-Disclaimer-
Please note that all of the above is purely opinion or common knowledge freely available to the public by BioWare and LucasArts sanctioned sources. I do not own Star Wars, or Star Wars: The Old Republic, which I think are the property of LucasArts Entertainment and BioWare/EA/LucasArts respectively.