I've found some time and money, so I think of buying SoU soon, so my question is: is it any good? Better OC then NWN? Any good modules for SoU?

Imo, the NWN story is better, but SoU OC has some cool features (Rangers and Druids can, for example, talk to a bunch of animals to get easy quests and xp. Plus Rangers can get more information from tracks, which are scattered all over the game) It's a bit short compared to NWN, but the fights are much tougher. SoU has some cool new creatures and items (especially misc. items) and you can punish that annoying Deekin (if you take him as an henchman). The final battle was horribly simple though. You'll know exactly what to do when you get in the 'arena', and then it's disappointingly easy without your henchman (keeps attacking the wrong things, idiot AI). I'd say it's worth it. It won't be as good as HotU imo, but it was still a cool game. Haven't played any modules for it though