Aw, I liked Demon Stone! I viewed it more as a hack-n-slash than an RPG - it doesn't have dialog trees/choices or side quests. But it was fun, and I liked the story well enough and the character banter. The gameplay was nice - I wish NWN had it, because combat-by-mouse-click is as boring as hell.
NWN... it was my first DnD RPG that I played, so the MQ wasn't so predictable to me. I think it would be more fun with mods. I liked the two expansion packs' main quests much better. I do wish it had more-interactive combat controls, but that's just the style of the thing. What I enjoyed in particular were the dialog trees, the integration of skills into dialog choices, and other non-combat elements. TES III and IV don't quite have that level of dialog tree sophistication. What I dislike the most about NWN - and possibly other games in that vein - is the necessity to "map out" your character build, lest you be crippled and have to start over again so that you can beat a boss battle. It dampens the flow of the game and spontaneity - for me, at least. I'd rather focus on the immediate gameplay and story than tally stat maths and skill point distribution. Fortunately, there are character build templates out there on the web, and if I play NWN again with mods, I'd probably use a template and just follow that so I don't have to fuss and fret over my character stats.
I can totally understand if people don't like NWN. I think I started a dozen characters but only really played with two or three. The first parts are tedious because your character is so weak and you have to baby him/her and you have crap equipment and the beginning quests are a bit dull, especially the fed-ex quests, and you can't do much because you have very few feat abilities.
Ya know, I have to say, even though I used to play D&D when I was much younger, I must have gotten really lucky with my characters on NWN. Two friends I introduced to NWN both had your complaint, that the characters they made were too weak to fight one boss or another and they didn't want to start over. But every character I've made, without ever following a particular template, or even pre-planning it ahead of time(always a "Wing it" kind of thing), has never had trouble on the game. I've made a Monk, a Wizard, a Cleric, a Druid, a Paladin, and a Rogue/Death Knight combo, and I've never been stopped by any particular encounter.