This is what I call a diamond in the rough.
TSL developer, Obsidian, took a rather conservative approach. They didn't bother making major upgrades to the tech, or perform major changes the gameplay, they just used what they had to make a game that, on the surface at least, looks very much like more of the same. However, a closer inspection reveals a few refinements, as well as new features, and of course, a new adventure to experience. So let's go into the details.
TSL picks up a few years after the events that took place in K1. The Republic is on the verge of collapse after the so-called Jedi Civil War, not to mention that the hero/villain from the first game, Revan, is missing. No one knows where he/she is or why he/she left in the first place. Anyway, you play the role of a former Jedi (and a General during the Mandalorian Wars), simply referred to as The Exile, that has been away from Republic space during the Jedi Civil War. What's worse, a new Sith threat has risen and is hunting the Jedi to extinction. And since your character is a former Jedi, prepare to be hounded by Sith at every turn. Initially, your only ally is an elderly woman named Kreia, but more people will join as you progress through the game.
There's a lot of backstory to the game, and the past is often discussed, much more often than in K1. However, through a few intelligently placed conversations, the game fills you in on all the essentials. Now, the game's story is great, despite having some plot holes due to cut content. And yes, it also has an unsatisfying ending, but that's mainly because it doesn't offer closure regarding your companions. However, the story does many things right, among which is letting you choose your motivation. Do you aid the Republic? Or do you sabotage it? This choice is present one way or another on every planet you'll visit. The choice might seem black and white at first, but throughout the game, the lines between the two options get kind of blurry. Because each faction involved (pro or anti-Republic) makes valid points. For sure, this is one of the game's major improvements over K1, which handled everything in a very black and white manner.
But you know, that's not the only story layer TSL has to offers, as the game puts significantly more importance on the personal stories of those involved in the Mandalorian Wars and the Jedi Civil War: common people, refugees, war veterans, former Jedi Knights, and of course, The Exile and his companions. Bottom line, there's a lot of story to explore in TSL, this being easily the best part about it. Its tone, and the often times stellar writing quality reminded me of Planescape: Torment, but it's not quite as coherent, the cut content being at fault here. However, it does offer interesting character interactions, and a good amount of choices as well. You'll even get a personalized ending where the game tells you how your actions affected the future of the various planets you've visited. In essence, it's like Fallout's ending slides, but without the slides part. This personalized ending goes a long way towards making the game's abrupt finale feel more satisfying, but that's just my opinion, you might disagree.
On a slightly story-related note, I feel the need to mention a feature that aides much in making character interactions feel meaningful: the influence system. What is this influence system? It's basically a set of variables that track how much a companion likes/dislikes you. This depends heavily on how you handle situations, as well as the personality of the companions themselves. For example, a certain assassin droid by the name of HK-47 may like you more when you behave like a (I'll quote him here) "random cruelty generator", while others may appreciate a more merciful approach. The system works quite well, and depending on the amount of influence you have with certain companions, you'll be able to make them Force users, not to mention that you'll uncover more of their backstory. Please note that it's impossible to max out your influence with all your companions, so one playthrough will not be enough to uncover their backstories in full, which is why this system also gives some extra replay value to the game. Bottom line, Obsidian deserves credit for implementing this system, and making it work quite well.
So far I've been going on about the story and characters, but I haven't mentioned the game's other elements. Well, as expected, TSL plays very much like K1, with no major differences and only a few improvements to the combat, a larger number of skill check situations (specially in dialogs), and a few extra feats and force powers for the character system. And speaking of the character system, this time around you'll start off as a Jedi, getting to choose between 3 base classes, while later in the game you'll get to choose between a few prestige classes. Which options are available to you depend on your character's alignment. And speaking of alignment, TSL uses the same Light Side/Dark Side alignment system from K1, which kind of goes against the story's gray tone. What this means is that many of your decisions (including many that are more on the neutral side) will be categorized as either Light Side or Dark Side, which feels out of place. Oh well...
One thing you'll be doing a lot in TSL is combat. Sadly, the game feels the need to shove combat down your throat just as often as its predecessor. So crappy 'dungeon crawls' abound. K1's Real-Time with Pause combat system was pretty 'flat'. It didn't feel satisfying, and it offered little in the way of tactics, besides choosing different attack types, items, or force powers to use. TSL's combat works the same way, though it looks a bit better due to some new character animations. As a new feature, TSL's combat also has a number of Forms to choose from. These forms tweak the way your character uses his/her lightsaber or force powers. For example, one lightsaber form can be more useful against Jedi, but at the expense of leaving you exposed to blaster fire. Another lightsaber form can offer a blaster fire deflection bonus, but it leaves you vulnerable to melee attacks. Force forms work much the same way, offering a set of benefits for certain situations, while also having a set of drawbacks to balance it all out. Besides these forms, TSL also gives you the chance to tweak your companion AI by choosing from a set of AI presets. For example, setting a companion to Ranged behavior will tell him/her to keep at distance from the target and use blasters, only switching to a melee weapon if the target gets too close for comfort. But ultimately, what do these improvements amount to? Not much really. The forms are a great idea and they work, but they add too little to make any real difference. Plus, the AI is just as dumb as it was in K1, and positioning your characters on the battlefield is still a dodgy operation due to the fact that you need to switch between characters and position them manually one by one. This system would have been better off using a point-and-click interface from the get go. It doubt it would've taken away anything from the cinematic look Bioware was aiming for in K1. But it's too late now. Bottom line: the combat is unsatisfying and there's too much of it.
Another new feature that TSL has to offer is item crafting. Yes, now you'll be able to break down all that junk you find throughout your voyage, and use the resulting parts or chemical components to create items you'll actually use. Kudos to Obsidian for doing this, it makes managing the inventory less of a chore, and puts to use some skills that otherwise would have seen little of that.
Since TSL uses pretty much the same tech as K1, the game doesn't look that great. What's worse, there's some occasionally sloppy level design, and overall, it just doesn't look quite as polished as K1 in this regard. TSL does have a larger selection of character faces however, which was definitely needed. Sound-wise, we have excellent voice acting (Sara Kestleman deserves a special mention, for her superb portrayal of Kreia), decent ambient sounds, and a pretty good soundtrack that fits the game's dark tone quite well. Other than that, TSL is known to have some compatibility problems with newer versions of Windows, as well as some bugs with certain driver editions from NVidia, and especially ATI. Usually, most of the bugs relate to the OS or the graphics driver. I've personally had little problems with the game, a one time save game corruption being the biggest issue I've encountered (thanks to autosaves it didn't cause any damage though).
All that being said, TSL is definitely a better game than K1, but the generally unpolished 'feel' it has, the few plot holes resulted from the cut content, the over-abundance of combat, and a rather unsatisfying ending drag it down, and make this only a near masterpiece. That being said, TSL is very much worth trying.