I am a fan of Computer RPGs which are featuring deep characters. The best example for this would probably be "Baldur's Gate 2" or "Planescape: Torment". For some reason I never happened to play the NWN series, so I would like to ask those of you who know, if NWN can be compared to to GB2 or PT in this aspect or not. And if so, both or just one of the NWN series?

Opinions vary on the main campaign of NWN2, I like it quite a lot myself.
But the expansion "Mask of the Betrayer" is widely considered to be the best thing since Torment.

I'd suggest playing both, especially as it's easier to get into game mechanics with original campaign,
than starting from lvl 20 in expansion. (supposed to be with the same character, but can start with new one).

NWN 1 is more combat, less roleplay. Though there are superb fan made campaigns out there.
Like these here, easily as good stuff as commercial releases.

Thanks for your fast answer. :-) I already suspected that it would rather be NWN 2 ...

With NWN 1 you have a single main character, and an have up to one companion with you, not counting summons if your class can do them. In NWN 2 you have a party again, like in Baldur's Gate, with you creating a main character and encountering new people through the story.

NWN1 is weak on characters. NWN1 shines in multi-player and fan made content/modules, but the OC is notoriously weak and it's NPC's are shallow and uninspired.

NWN2 is better for SP, especially in regards to NPC henchmen. If you are looking for a BG style party dynamic that would be the best place to go.

Right, never did finish that campaign, just the original and the first expansion, my bad.
In the case of single character vs party I tend to favour parties because they allow me to explore the dynamics between different people and I just love that.

Both NWN are greatest in multilayer and my notes are under this observation, I spent more than 500 hours on each one, polished my skills and even learned the bases for my engineering.

However, NWN1 is a strange adaptation to the D&D 3.0 and Forgotten Realms meanwhile NWN2 is more closest to the D&D 3.5 and the Forgotten Realms.

By example, NWN1 have unique art for creatures meanwhile NWN2 is very loyal to the art in the D&D Monster manual (very noticeable with the demons and dragons). NWN1 lets stack attributes scores from multiples items when that is not the case in the D&D rules. I.e. Ring +2 Intellect, Necklace +6 Int gives +8 to the character .

More important, the prestige classes are better in NWN2 (well for wizards) and by last, the STorm of Zehir campaign on NWN2 is very funny as let you handle 4 custom PC plus 1-2 cohorts.

For PW quality, NWN2 was "poor" due the Electron Toolset requirements however, the greatest bane from 6 years ago were average BW and hard disk space from the players, two things I think are more or less solved by now. One quick example: the full NWN1's PW I helped to create were 30 MB, when I begin to make experiments with NWN2 one single are from the PW was heavy than that (If you wanted to reach the rich details than Mask of Betrayer had in the scenarios). But I had equally good experience with NWN2 multiplayer than the NWN1

P.d. Nwn1 is poor with the OC because originally was to be only the toolset (something like RPGMaker but with D&D 3.0 settings) and by last minute the OC was added. NWN2 toolset was originally poorest than the NWN1 because the center was the OC with the plus of the toolset. However, the bigger support are in NWN1 with the CEP expansion.

Not the be 'that guy', but I don't think that addresses OP's interest in 'deep characters'.

@OP: If you are looking for deep characters, then avoid NWN 1. The characters in the OC have all the depth of a teaspoon, and from what I have heard about the expansions, the characters are similarly shallow there, with the possible exception of comic relief in the form of a particular kobold. As for NWN 2, the characters are fairly fleshed out, but the rather irritating 'influence' system, combined with the fact that you get very few opportunities to get it and that influence thresholds are so damn high, means that you pretty much need to gain the system in order to get them to open up to you and help them develop character; for instance, there is a character who has abandoned their clan, and when confronted with the consequences of leaving, you must not try to do anything other than agree with everything that character said, otherwise they get pissy and you lose influence with them. NWN2 MotB has far deeper characters and story, and fixes the influence system by making it easier to get (both by drastically upping the amount of influence gained per hit and providing many more opportunities to gain it).

It's my understanding that this discrepancy was due to the fact that D&D 3.0 and NWN were being developed simultaneously. By the time the pen and paper ruleset and art was finalized, NWN was way too far along in development to go back and change these things. I've heard this story as well, and it makes sense. Each chapter is a strange mix of stand-alone areas strung together tenuously by a plot that seems utterly irrelevant to the tasks at hand. When they got their act together and actually designed something cohesive in SoU and HotU it worked like a charm.

True, my error, anyway, helping the OP NWN1 first OC is very bad with the Deep character development, the other 2 as one whole are a little better similar to the BG1 (AKA: Minimum). The premium content in the NWN1 are OK, they had potential but are very short (The last one I hate it).

NWN2 PC development... was based in BG (San Wikipedia) but... even the Paladin don't quit or try to kill the evil ranger (Nothing like Keldorn and Viconia), the first expansion, I liked a lot with the NPC interaction with your character. Third expansion is more like the BG1 and Icewindale series, you developed your PC and going to the adventure, not PC development is involved there. The premium content... seem to be similar to the one from NWN1.

And again, you want PC deep development? Try the Persistent Worlds available in either version, there is where them become gems