I haven't played BG in several years, but Amber is the best npc mod I've tried. A good thief is necessary for BG2, and you just can't count on you-know-who, and you can't even get him in ToB. I find Jan Jansen just as irritating as most of the "Good" npc's. So you need "Good" a thief, but her romance path is too sweet to resist! I've played Fade, but found getting her to join happens too late in the game. I have the same problem with Skie. I'm gonna try Dace, next. Even if Dace proves more interesting, it's going to be real hard to resist playing Amber, should I ever play this game again. I suspect Dace is going to be a pain if I don't commit the occasional rape and murder along the way.
I would rank Amber and Level1npc's as essential mods for the game. With these two modes, you can make Imoen useful, and Amber kicks out nicely, right when you're done with her. Isn't that convenient? She volunteers to make room for Imoen, and the stock Imoen is useless when you need a thief, There must be another mod that changes Imoen into a raising thief, but Level1npcs is versatile, if cumbersome. I digress
I've had no problems with this mod. Amber is a little tricky to find at the beginning of the game, but she's well worth it. I really hate trading her in for Imoen, but she's written for doing just that. I'm going to have to see if I can summon her in ToB. Imoen starts to grate after a while.