I was rather annoyed when I heard that BioWare decided against doing the sequel, after the monumental job they did with the first. Apparently they had an iffy experience working with the Publisher LucasArts, and they decided to go and create their own IP's. So Obsidian Entertainment, who BioWare recommended to LucasArts, took over the mantle for the second game in the series.
You'll find right from the start, that the game is a lot darker and much more mysterious than the first game. You play a new character, the Exile, who served Revan during the Mandalorian Wars. When Revan turned on the Republic, he joined Revan and fought against the Republic forces. Eventually, you come to realise the error of your ways and you return to face the Jedi Council on Dantooine. They strip you of your powers, and you are exiled from the order. You spend the next 10 or so years wandering the outer rim of the galaxy, keeping a low profile. (the game is set 5 years after the original)
And this is where you pick off. The game starts off in an all too familiar fashion. (You wake up on a ship and had a memory loss etc etc) And for the first 6/7 hours, you really dont know why and where you are. You're main goal is to escape the place safely, and once you do that, everything becomes a little clearer.
There are certain things I liked and didnt like about KOTOR2. The gameplay was much improved for one. You'll find levelling up is a lot easier and quicker, and because of that you'll get a lot of force powers from the early stages of the game. This makes it a lot more fun, but does make the game a bit too easy.
The NPC characters are very good. Again like in the first, during quests in each of the planets you'll build a team mixed with characters with all sorts of special skills. You dont really form a bond with any of the characters though, and you always feel rather suspicious of them. There's very little trust, and you're always weay of what everyone is up to. This is what I meant about the game being a bit darker and more mysterious in the first.
The game lacks a good romance too. In the first, the romance with Bastila/Carth played a massive role in the storyline for a lot of people. But there are no real engaging romances in KOTOR2, which is slightly disappointing. The story feels some what less engaging than the first because of this.
The storyline is solid, but it's very incomplete. The ending is very hard to understand, and it's pretty poor unsatisfying to be honest. I guarantee when you see the closing creditscome on screen at the end of the game, you'll go "That cant be it!??". The truth of the matter is LucasArts told Obsidian to finish the game in just 14 months(this was to get the game out in time for Xmas 04) and because of this, the game suffered. There was a lot of cut content, including quests, cutscenes, and dialagous. There are a lot of annoyings bugs aswell.
I'm sure, that if LucasArts had of given Obsidian the time they gave BioWare to do the first, that the game would of been admired as an excellent sequel. Obsidian did an excellent job with it, and if there is to be a KOTOR3, I would be very happy if they were to do it.
So in the end, if you played the first and loved it, you almost have to at least try this. I found the first playthrough rather disappointing, but on my second playthrough I enjoyed it more. There's a different structure for the game than the first, and it might take some getting used to before you can really appreciate the game. Some will like it, others mightnt.