Andikki: Triss is my main (if not the only) complaint in the game. I read the books a long, long time ago - probably in school, and I don't remember much, but my impression of Triss was completely different. I think I remember Yennefer as the "cool" one and Triss as the "nice" one. Now the game's Triss isn't nice at all, plus she's wearing that slutty outfit and her face doesn't look very pleasant to me. Shani isn't very exciting, and I would have prefered to stay a lone witcher, but I think the game didn't give such an option (or did it?), so I ended up with Shani just to keep Triss away. The lesser of two evils =D
So count +1 in the anti-Triss camp.
You are correct; in the books, Yennefer is cool, and Triss is nice. I think Triss is still nice in the game, but her political deals get her into trouble. She's really not ruthless enough for them. Eskel sums her up nicely in the prologue when he explains to Geralt why they won't show Triss the lab: she'd want to use witcher secrets to help people, heal illnesses, etc., but it's never that simple. I agree with you that her costume is atrocious. Fish net and a wide fur collar? Really?