A definite improvement over the original but still lacking in some of the immersion and depth missing from the original.
The party system in the original game was failrly weak. In NWN2, the system is much more like you'd find in a typical RPG. You've got full control over all of the members in your party and you can have up to four (or five depending on where in the game) party members at any one time. You've got full control over their inventories and skills and how they level up.
In a departure from most RPGs and all the previous Bioware games, NWN2 adopted an experience point system that's a lot like KotOR. Your NPCs don't get experience points. They always have the same experience points (and thus the same level) as your character. You don't need to worry about keep a small number of characters in your party to avoid dividing up the xps. Also, if a character is not currently in your party and you swap him in later, they will immediately jump up to your experience level. Sometimes, if you haven't played with the character for a while, you'll have numerous level-ups for the character. You don't have to worry about picking favorites and leaving the other characters too weak to use later.
The interface is also dramatically different. There's no more radial menu. The general idea is that you should be able to perform any action with one or two mouse or keypresses. A single click will get you access to all of your skills or magic abilities. You can also move around the numerous skill, inventory and ability panels or remove the ones you don't want. The game also adds a hotkey bar where you can add up to 12 skills, spells or usuable items. You can even add stack a weapon and a shield so you can quickly switch from ranged to melee combat. You can also create up to 10 hotkeys bars giving you 120 slots which is total overkill and laughable.
There are a few annoying things missing from the interface that a pretty basic and you'd think they would have put them in. One is the ability to multi-select characters. You can't give instructions to all of your characters at once. If you want your entire party to attack a particular enemy, you have to issue instructions to each one individually.
The game also puts more emphasis on your non-combat skills. Things like persuasion, intimidation, intelligence, etc, have lots of opportunities to affect conversations. You can earn additional experience points by following the right conversions and sometimes you can even avoid entire battles.
The camera control is also dramatically different. There are four different modes (each with a number of options) that define how the camera works. You can pick a typical overhead view that pans like the original game. You can pick a chase camera or a moveable third person, over-the-shoulder camera. You can get the game in a mode that's almost like a first/third person shooter, but it doesn't quite get there. There's quite a lot of flexibility and anyone should be able to find something that works for them. I found that even though I was happy with the modes, I never did find the right settings where everything just clicked and it felt perfect.
My biggest complaint with the game is that the content isn't written terribly well. The game doesn't really pull you into the story and compel you to keep playing. The original game suffered from this as well. The game is almost entirely linear. There are a number of side quests, but most of them you'll complete automatically as you complete the main quest. The individual areas also feel sparse and you can't escape the feeling you're playing a game. You'll enter the city of Neverwinter and find quite a number of openable (but locked) doors throughout the city. Unfortunately, you can't go in any of them. They'll each open up one by one as the appropriate moment in the quest line progresses. Not very realistic. All-in-all, I couldn't help by feel that that game was just a bit dry.
One interesting part of the game is the keep. Late in the game, you acquire a keep that you can control. You get to repair and build it over time. You get to hire soldiers, send them on missions and decide how to handle your neighboring lands. It's relatively interesting, but unfortunately you get the keep quite late in the game. If you could get it earlier and have it as a backdrop for the whole game, that would have made it more interesting; adding it too late was a mistake in my opinion.
One big plus for the game is that it is long. This is not a cheap game that'll last for a few hours. The main quest line is one of the longest I've ever played and doesn't leave you feeling disappointed. The soundtrack is also pretty good with over three hours of unique music.
An odd complaint I have about the game is that there are too many unique and interesting items. I usually complain that games have too little and are filled with boring items that are nothing more than stats. Baldur's Gate is a great example of interesting items. The game mostly has the boring and plain stuff, but there's a good amount of interesting, unique items with cool stories behind them. NWN2 went too far. Toward the end of the game, almost every item you find seems to be an expensive, powerful item - far more than you can use and even more than you can sell. At some point, you lose interest and don't care about the new armor or sword you just found.
The graphics are okay. They are right about where you'd expect them to be but aren't anything new and exciting. The areas have a bit of a constrained feeling to them where you can't wander off the path and into the surrounding area - a bit like KotOR or Fable - and the visuals fade off in the distance instead of providing long range viewing like Oblivion or Gothic.